1. States of matter + 2. Atoms, elements and compounds Flashcards
(831 cards)
1
Q
Diffusion
A
The automatic mixing of liquids and gases as a result of the random motion of their particles
2
Q
What sort of particles diffuse the quickest?
A
Small, light ones.
3
Q
Does diffusion take place faster in a liquid or a gas?
A
Gas, move around faster, more chance of a collision.
4
Q
Elements
A
Substances made up of only one type of atom.
5
Q
Compound
A
A substance made out of two or more elements chemically bonded together.
6
Q
Mixture
A
When substances are mixed together and intermingle but do not react.
A mixture is not a pure substance.
7
Q
Atomic no.
A
No. of protons.
BOTTOM NUMBER
8
Q
Atomic Mass no.
A
No. of protons plus neutrons.
TOP NUMBER
9
Q
No. of Protons =
A
No. of electrons.
10
Q
What does the number of electrons on the outer shell of an element tell us?
A
What group it is in, and how it reacts.
11
Q
Why does the relative atomic mass only count protons and neutrons?
A
Because electrons weigh 1/2000 of what protons and neutrons weigh, so are generally discounted.
12
Q
Isotopes
A
Atoms of the same element with different numbers of neutrons.
13
Q
Describe the attractive forces in solids
A
Strong forces of attraction between particles, particles are packed very closely together in a fixed and regular pattern
14
Q
Describe the attractive forces in liquids
A
Weaker attractive forces in liquids than in solids, particles are close together in an irregular, unfixed pattern
15
Q
Describe the attractive forces in gases
A
No intermolecular forces, particles are in random movement and so there is no defined pattern
16
Q
Describe the movement in solids
A
Atoms vibrate in position but can’t change position or move
17
Q
Describe the movement in liquids
A
Particles can move and slide past each other which is why liquids adopt the shape of the container they’re in and also why they are able to flow
18
Q
Describe the movement in gases
A
Particles are far apart and move quickly (around 500 m/s) in all directions, they collide with each other and with the sides of the container (this is how pressure is created inside a can of gas)
19
Q
Describe the fixed volume and density in solids
A
solids have a fixed volume, shape and high density
20
Q
Describe the fixed volume and density in liquids
A
Liquids have a fixed volume but not a fixed shape and have a moderate to high density
21
Q
Describe the fixed volume and density in gases
A
No fixed volume, since there is a lot of space between the particles, gases can be compressed into a much smaller volume. Gases have low density
22
Q
What change occurs during melting?
A
Melting is when a solid changes into a liquid
23
Q
What does melting require?
A
Requires heat energy which transforms into kinetic energy, allowing the particles to move
24
Q
When does melting occur?
A
Occurs at a specific temperature known as the melting point (m.p.) which is unique to each pure solid
25
What change occurs during boiling?
Boiling is when a liquid changes into a gas
26
What does boiling require?
Requires heat which causes bubbles of gas to form below the surface of a liquid, allowing for liquid particles to escape from the surface and within the liquid
27
When does boiling occur?
Occurs at a specific temperature known as the boiling point (b.p.) which is unique to each pure liquid
28
What change occurs during freezing?
Freezing is when a liquid changes into a solid
29
When does freezing occur?
This is the reverse of melting and occurs at exactly the same temperature as melting, hence the melting point and freezing point of a pure substance are the same. Water for example freezes and melts at 0ºC
30
What does freezing require?
Requires a significant decrease in temperature (or loss of thermal energy) and occurs at a specific temperature which is unique for each pure substance
31
What change occurs during evaporation?
When a liquid changes into a gas.
32
What is the difference between boiling and evaporation?
Evaporation occurs only at the surface of liquids where high energy particles can escape from the liquid’s surface at low temperatures, below the b.p. of the liquid
33
What increases the rate of evaporation?
The larger the surface area and the warmer the liquid/surface, the more quickly a liquid can evaporate
34
What is required for evaporation? (if anything)
No energy is required for evaporation to occur and it takes place over a range of temperatures
35
What change occurs during condensation?
When a gas changes into a liquid, usually on cooling
36
How does condensation occur (in terms of particles)?
When a gas is cooled its particles lose energy and when they bump into each other they lack the energy to bounce away again, instead they group together to form a liquid
37
What is required for condensation? (if anything)
No energy is required for condensation to occur and it takes place over a range of temperatures
38
What change occurs during sublimation?
When a solid changes directly into a gas
39
What example of solids can undergo sublimation?
This happens to only a few solids such as iodine or solid carbon dioxide
40
What is the reverse reaction of sublimation?
The reverse reaction also happens and is also called sublimation (sometimes called deposition or desublimation)
41
When does sublimation occurr?
Sublimation occurs at a specific temperature which is unique for a pure substance
42
In what type of motion are gaseous particles in?
Gaseous particles are in constant and random motion
43
What happens to gaseous particles when there is an increase in temperature?
An increase in temperature increases the kinetic energy of each particle, as the thermal energy is transformed to kinetic energy, so they move faster
44
What causes pressure in a container?
The pressure that a gas creates inside a closed container is produced by the gaseous particles hitting the inside walls of the container.
45
What is the effect of increasing temperature on pressure?
As the temperature increases, the particles in the gas move faster, impacting the container’s walls more frequently
Therefore an increase in temperature causes an increase in pressure
46
Brownian Motion definition
Brownian motion is defined as the random movement of particles in a liquid or a gas produced by large numbers of collisions with smaller, often invisible particles
47
What does the observation of brownian motion prove?
the correctness of the kinetic particle theory
48
Diffusion definition
This is the process by which different gases or different liquids mix and is due to the random motion of their particles
49
From where to where do diffusing particles move?
Diffusing particles move from an area of high concentration to an area of low concentration, till the concentration of particles is even
50
Does diffusion require energy?
NO
Diffusion happens on its own and no energy input is required although it occurs faster at higher temperatures
51
What is the basis of the kinetic theory of matter?
When substances are heated, the particles absorb thermal energy which is converted into kinetic energy
52
What happens when you heat a solid?
Heating a solid causes its particles to vibrate more and as the temperature increases, they vibrate so much that the solid expands until the structure breaks and the solid melts
53
What happens when you heat a liquid?
On further heating, the now liquid substance expands more and some particles at the surface gain sufficient energy to overcome the intermolecular forces and evaporate
54
What happens when the b.p. temperature is reached in a liquid?
When the b.p. temperature is reached, all the particles gain enough energy to escape and the liquids boils
55
What type of graph can be used to show how changes in temperature affect changes in state?
A heating curve - solid to gas
A cooling curve - gas to solid
56
What is an example of Brownian Motion?
An example of Brownian motion is the observed jerky and erratic motion of smoke particles as they are hit by the unseen molecules in the air which can be seen under a microscope
57
What is the basic condition needed to show the Brownian process is occurring?
In all cases, larger and visible particles are caused to move by the random bombardment of smaller, invisible particles
58
In what state does diffusion happen the fastest?
Diffusion occurs much faster in gases than in liquids as gaseous particles move much quicker than liquid particles
59
Do gases diffuse at different rates at the same temperature?
YES
- At the same temperature, different gases do not diffuse at the same rate.
60
What causes the difference in the rate of diffusion in gases?
This is due to the difference in their relative molecular masses
61
At what relative molecular mass do gas particles diffuse the fastest?
Lighter gas particles can travel faster and hence further, therefore the lower its relative mass the faster a gas will diffuse
62
What are the three states of matter?
Solids
Liquids
Gases
63
What state you get depends on what?
How strong the forces of attraction are between the particles of the material
64
How strong the forces are depends on what three things?
The material
The temperature
The pressure
65
Describe the formation of solids (attraction? shape? movement?)
Strong forces of attraction between particles holding them together in a fixed position to form a very regular lattice arrangement.
The particles don’t move from position so keep a definite shape and volume.
The particles vibrate about their position - the hotter the solid becomes the more it vibrates (causes them the expand slightly)
66
Describe the formation of liquids (attraction? shape? movement?)
Weak forces of attraction between the particles. Randomly arranged and free to move past each other - stick close together
Have a definite volume but don’t keep a definite shape- flow to fill container
Particles are constantly moving with random motion. The hotter the liquid gets the faster it moves causes them to expand slightly
67
Describe the formation of gases (attraction? shape? movement?)
No forces of attraction between particles (very weak if any) Free to move and are far apart. Particles travel in straight lines
Don’t keep a definite shape or volume and will always fill container
Particles move constantly with random motion. The hotter it gets the faster they move . They expand when heated and pressure increases.
68
What is a physical change?
When the particles don’t change just their arrangement or energy
69
Solid - Liquid
Melting
70
Liquid - Gas
Evaporating
71
Gas - Liquid
Condensing
72
Liquid - Solid
Freezing
73
Solid - Gas
Subliming
74
What do melting and evaporating and subliming have in common?
Heat energy is supplied between the state
75
What do freezing and condensing have in common?
Heat energy is given out between the states
76
Describe the energy of the particles from a solid to a liquid
When the solid is heated its particles gain more energy. This makes them vibrate more which weakens the forces of attraction holding the solid together making the solid expand.
At a certain temperature the particles have enough energy to break free from their positions. This is melting (solid - liquid)
77
Describe the energy of the particles from a liquid to a gas
When a liquid is heated the particles have more energy. The energy makes the particles move faster weakening and breaking the bonds holding the liquid together.
At a a certain temperature the particles have enough energy to break their bonds. This is evaporating (liquid - gas)
78
What three experiments can be used to show the movement of particles?
Potassium Manganate(Vll) and water
Ammonia and Hydrogen Chloride
Bromine gas and air
79
Define the process evident in all three experiments
Diffusion - the movement of particles through a liquid or gas from an area of high concentration to an area of lower concentration until a uniform concentration is achieved
80
Describe the potassium manganate experiment with water
1) Get a beaker of water and place some potassium manganate at the bottom
2) Watch as the purple colour of the potassium manganate slowly spreads to fill the beaker - this is diffusion as the particles are diffusing out among the water particles
81
What causes the particles in the potassium manganate to eventually spread out evenly?
The random motion of particles in a liquid
82
What happens if you add more water to the final solution of the potassium manganate?
The potassium manganate would spread out even further apart and the solution would be less purple because of dilution
83
What does aqueous ammonia and hydrochloric acid give off?
Aqueous ammonia - ammonia gas
Hydrochloric acid - Hydrogen chloride gas
84
How should you set up the experiment with ammonia and hydrogen chloride?
In a glass tube have a cotton wool soaked in aqueous ammonia at one end and at the other, cotton wool soaked in hydrochloric acid.
85
What happens in the ammonia and hydrogen chloride experiment?
The ammonia gas diffuses from one end of the tube and the hydrochloric acid diffuses from the other. When they meet they react to form ammonium chloride (a white ring in the glass tube)
86
Describe the experiment using bromine gas?
Fill half a gas jar with bromide gas and the other with air - separate with gases with a glass plate. When you remove the glass plate watch how the bromide gas slowly diffuses through the air.
86
What is bromine?
A brown gas that is very smelly
86
What causes the bromine to eventually diffuse right through the air?
The random motion of the particles
86
Why doesn’t the ring of ammonium chloride form in the middle?
If forms closest to the end of the tube where the hydrochloric acid was because the particles of ammonia are smaller and lighter than the hydrogen chloride, so diffuse through the air more quickly
87
What is a atom?
The smallest particle of a chemical element that can exist - all substances are made up of atoms
88
What is a molecule?
A group of atoms bonded together by covalent bonds (can be made up of one element or more than one element)
89
What is an element?
Substances that consist of one type of atom that cannot be broken down any simpler by use of heat or electricity
90
Give an example of an element
Copper (any element in the period table)
91
What is a compound?
Substances made up of two or more different elements which are chemically joined together
92
Give an example of a compound and how it is formed
Carbon dioxide - One carbon atom has boned with two oxygen atoms to form a molecule of carbon dioxide, with the formula CO2
93
Why is it very difficult to separate two original elements after they have been chemically combined? Give an example
The properties of the compound are often totally different from the properties of the original element.
For example a mixture of iron and sulphur is heated and react togetehr to form iron sulphide. Iron sulphide isn’t like iron (not attracted to a magnet) nor like sulphur (not yellow)
94
What is a mixture?
Molecules of elements and mixtures simply mixed together without chemical bonds
95
Give two examples of a mixture
1) Air - is a mixture of gases mainly nitrogen, oxygen, carbon dioxide and argon
2) Crude oil - mixture of different lengths hydrocarbon molecules
96
Can you separate mixtures easily and if so, with what methods?
Yes - there are no chemical bonds between the different parts of a mixture so can be separated by the following physical methods;
Distillation
Fractional
Filtration
Crystallisation
Paper chromatography
97
What is a solvent?
The liquid in which a solute dissolves
98
What is a solute?
The substance that dissolves in a liquid to form a solution
99
What does soluble mean?
A substance that can dissolve
100
What does insoluble mean?
101
What does insoluble mean?
A substance that cannot dissolve
102
What is filtration used to separate?
Insoluble solids from a liquid (and purification)
103
What is crystallisation used for?
104
What is crystallisation used for?
Separating soluble solids from a solution
105
What is the method for crystallising a product?
Pour solution in evaporating dish
Slowly heat until crystals start to form then stop *solvent evaporates solution making it more concentrated
Remove dish from heat and put in warm place *rest of solvent will evaporate
Dry the product (either in a drying oven or desiccator)
106
What does a desiccator contain?
Chemicals that remove water from the surroundings
107
What can you separate using both filtration and crystallisation!
Rock salt
108
What is rock salt and what is it about their physical properties that make them easy to separate?
Rock salt is a mixture of salt and sand. Salt and sand are both compounds but salt dissolves in water and sand doesn’t
109
Give the four steps for separating rock salt
1) Grinding - grind rock and salt with a pestle and mortar
2) Dissolve - dissolve in beaker and stir
3) Filtering - filter through filter paper in a funnel
4) Crystallisation - evaporate in a evaporating dish
110
Why does sand collect in the filter paper?
It is insoluble (doesn’t dissolve), so stays as big grains. These wont fit through the tiny holes in the filter paper
111
Why does salt go through the filter paper?
It is soluble and dissolved in the solution - when water is evaporated from it, the salt forms a crystal in the evaporating dish
112
What is chromatography in particular paper chromatography?
Another method for separating out mixtures - paper chromatography separates out dyes
113
What happens in the ammonia and hydrogen chloride experiment?
The ammonia gas diffuses from one end of the tube and the hydrochloric acid diffuses from the other. When they meet they react to form ammonium chloride (a white ring in the glass tube)
114
Go through the method of chromatography
1) Draw a line near the bottom of the filer paper (in pencil)
2) Add spots of different dyes to the line in regular intervals
3) Attach a lollipop stick to the top of the sheet and dip a tiny bit of the paper into beaker of solvent
4) The solvent seeps up the paper carrying the dyes with it
5) Each dyes moves up at different rates and forms spots
6) The end result is called chromatogram.
115
Why should you draw the line with pencil not pen?
Pencil marks are insoluble and wont react with the solvent
116
Why does chromatography seperate mixtures?
It works because different dyes move up the paper at different rates. Some stick to the paper and others will dissolve more readily in the solvent and travel more.
116
When you dip the paper in the solvent why should you make sure that the dyes aren’t touching the solvent?
So they don’t dissolve in it
117
When you dip the paper in the solvent why should you make sure that the dyes aren’t touching the solvent?
So they don’t dissolve in it
118
The distance the dyes travel up the paper depend on what?
The solvent and the paper used
119
How can chromatography help identify dyes?
You can work out dyes that are present in an unknown substance by making chromatograms of the unknown substance and for some reference materials (dyes you think are in it)
You then compare the chromatograms - spots on the chromatograms roe the unknown that match the spots on the chromatograms of the reference materials means the dyes are the same
120
What happens in the ammonia and hydrogen chloride experiment?
The ammonia gas diffuses from one end of the tube and the hydrochloric acid diffuses from the other. When they meet they react to form ammonium chloride (a white ring in the glass tube)
121
When you dip the paper in the solvent why should you make sure that the dyes aren’t touching the solvent?
So they don’t dissolve in it
122
The distance the dyes travel up the paper depend on what?
The solvent and the paper used
122
What are the two types of distillation called?
Simple and fractional
123
How can chromatography help identify dyes?
You can work out dyes that are present in an unknown substance by making chromatograms of the unknown substance and for some reference materials (dyes you think are in it)
You then compare the chromatograms - spots on the chromatograms roe the unknown that match the spots on the chromatograms of the reference materials means the dyes are the same
124
When you dip the paper in the solvent why should you make sure that the dyes aren’t touching the solvent?
So they don’t dissolve in it
125
Describe what happens in simple distillation
1) The solution is heated - the part with the lowest bp evaporates
2) The vapour is then cooled, condenses (turns back to a liquid) and collected
3) The rest of the solution is left behind in the flask
126
Give an example of a solution you could seperate in simple distillation
Pure water from seawater - you’ll end up with salt left in the flask
127
What is the problem with simple distillation which makes fractional distillation better?
You can only separate things with very different bp in simple distillation
128
Give an example of a solution you could seperate in simple distillation
Pure water from seawater - you’ll end up with salt left in the flask
128
When you dip the paper in the solvent why should you make sure that the dyes aren’t touching the solvent?
So they don’t dissolve in it
129
Why does chromatography seperate mixtures?
It works because different dyes move up the paper at different rates. Some stick to the paper and others will dissolve more readily in the solvent and travel more.
130
The distance the dyes travel up the paper depend on what?
The solvent and the paper used
131
How can chromatography help identify dyes?
You can work out dyes that are present in an unknown substance by making chromatograms of the unknown substance and for some reference materials (dyes you think are in it)
You then compare the chromatograms - spots on the chromatograms roe the unknown that match the spots on the chromatograms of the reference materials means the dyes are the same
132
What are the two types of distillation called?
Simple and fractional
133
Describe what happens in simple distillation
1) The solution is heated - the part with the lowest bp evaporates
2) The vapour is then cooled, condenses (turns back to a liquid) and collected
3) The rest of the solution is left behind in the flask
134
Give an example of a solution you could seperate in simple distillation
Pure water from seawater - you’ll end up with salt left in the flask
135
What is the problem with simple distillation which makes fractional distillation better?
You can only separate things with very different bp in simple distillation
136
Describe what happens in fractional distillation
1) You put your mixture in a flask then stick a fractionating column on top - heat it
2) The liquid with the lowest bp evaporates first (when the temp on the thermometer matches the bp it reaches the top of the column)
3) Liquids with the highest bp might also evaporate (only bet part of the way before condensing because column is cooler
4) When the first liquid has collected you raises the temperature until the next one reaches the top
137
What is simple distillation used to seperate out?
Solutions - liquids
138
What do atoms consist of?
A central nucleus, composed of protons and neutrons, surrounded by electrons, orbiting in shells
139
What makes the nucleus have a positive charge? Why is almost the whole mass of the atom concentrated in the nucleus?
The protons are heavy and positively charged
140
Describe a neutron and electron
Neutrons are heavy and have a neutral charge
- Protons are tiny and light and have a negative charge
141
What is the relative mass and charge of protons, neutrons and electrons?
Proton - mass 1, charge +1
Neutron - mass 1, charge 0
Electron - mass 1/2000, charge -1
142
What is the atomic number?
The number of protons
143
Where does the mass number next to the symbol of the element?
Top left hand corner
144
Where does the atomic number go next to the symbol of the element?
Bottom left hand corner
145
What is the mass number?
The number of protons and neutrons
146
How do you work out the number of neutrons?
Subtract the atomic number from the mass number
147
Atoms of the same element all have what the same?
The number of protons
148
Atoms of different elements will have different what?
Number of protons
149
What is the relative atomic mass?
A measure of the mass of one atom of the element compared with the mass of an atom of C-12 (mass is exactly 12) - the average mass of all isotopes of an element
150
What two things do you need to know to work out the relative atomic mass?
Relative mass of each isotope and its relative abundance
151
What does the relative abundance mean?
How much there is of the each isotope compared to the total amount of the element in the world
152
What is the equation for working out the relative atomic mass?
(% of isotope 1 × mass of isotope 1) + (% of isotope 2 × mass of isotope 2) ÷ 100
153
What is an isotope?
Atoms that have the same number of protons and electrons but different number of neutrons
same proton number
different mass numbers
154
Give an example of an isotope
C-12 and C-14 (used in carbon dating)
155
What does the period table show?
Elements put in order of increasing atomic number
156
How is the period table laid out?
Elements with similar properties are put in the same column (group)
157
What group the elements are put into corresponds to what?
The number of electrons the elements have on their outer shell (group 1 have 1, group 2 have 2…) This is why there properties are similar
158
What are the five electron shell rules?
1) Electrons always occupy shells (energy levels)
2) Lowest energy levels are always filled first - closest to the nucleus
3) Only a certain number of electrons are allowed in each shell
4) Atoms are happy when they have full electron shells - like the noble gases
5) In most atoms the outer shell is not full making the atom want to react
159
What are the certain number of electrons allowed in each shell?
1st shell = 2
2nd shell = 8
3rd shell = 8 (still filling)
160
What is the electronic configuration?
The distribution of electrons in an atom
161
How do you work out the electronic configuration?
Use your period table and the electron shell rule (atomic number = protons and the no. of protons = no. of electrons)
162
What are the electronic configurations of the first 20 elements?
Atomic numbers;
H - 1
He - 2
Li - 3
Be - 4
B - 5
C - 6
N - 7
O - 8
F - 9
Ne - 10
Na - 11
Mg - 12
Al - 13
Si - 14
P - 15
S - 16
Cl - 17
Ar - 18
K - 19
Ca - 20
H - 1
He - 2
Li - 2.1
Be - 2.2
B - 2.3
C - 2.4
N - 2.5
O - 2.6
F - 2.7
Ne - 2.8
Na - 2.8.1
Mg - 2.8.2
Al - 2.8.3
Si - 2.8.4
P - 2.8.5
S - 2.8.6
Cl - 2.8.7
Ar - 2.8.8
K - 2.8.8.1
Ca - 2.8.8.2
163
What is the number of outer electrons in each of the following groups?
Group 1
Group 2
Group 3
Group 4
Group 5
Group 6
Group 7
Group 0
Group 1 - 1
Group 2 - 2
Group 3 - 3
Group 4 - 4
Group 5 - 5
Group 6 - 6
Group 7 - 7
Group 0 - 0
164
What is diffusion?
the movement of particles from a region of high concentration to a region of lower concentration
165
What is Brownian motion?
random molecular bombardment of large visible particles by molecules, atoms or ions
166
Where is evidence for Brownian motion?
Observations of the motion of tiny visible particles suspended in liquids or gases
167
Why is rate of diffusion dependent on molecular mass?
Greater the molecular mass => heavier the molecule
Molecules with lower mass move faster than those with higher mass
Lighter molecules diffuse faster than heavier molecules
168
What is the kinetic theory? (3)
All matter consists of particles
There are forces of attraction between the particles
Particles possess kinetic energy to vibrate and move
169
What is the relative charge of a proton?
+1
170
What is the relative charge of a neutron?
no charge
171
What is the relative charge of an electron?
-1
172
What is the relative mass of a proton?
1
173
What is the relative mass of a neutron?
1
174
What is the relative mass of an electron?
0.00054 (1/2000)
175
What is a proton number?
number of protons in the nucleus of an atom
176
What is a nucleon (mass) number?
total number of protons and neutrons in the nucleus of an atom
177
What are isotopes?
atoms of the same element which have the same proton number but a different nucleon number
178
Why do isotopes have the same properties?
they have the same number of electrons in their outer shell
179
What are the two types of isotopes?
radioactive
non radioactive
180
What is a medical use of radioisotopes?
Sterilizing equipment
Cancer treatment
181
What is an industrial use of radioisotopes?
Checking for oil leaks in pipelines
182
What is an element?
A substance made of one type of atom
183
What is a mixture?
substance contains two or more elements or compounds that are not chemically bonded together
184
What is an alloy?
a mixture of a metal with other elements
185
What is an ion?
Electrically charged particle
185
How are ions formed?
Electron loss/gain
185
What is a compound?
substance made up of two or more different types of atoms joined together by chemical bonds
186
What is an ionic bond?
Attraction between positive ions and negative ions
187
What is an ionic bond between?
Metals + non-metals
188
How are ionic bonds formed?
Ions transfer electrons from one atom to another
189
An ionic lattice has + & - ions and is held together by
strong electrostatic bonds
190
What are 4 properties of ionic compounds?
High fixed points
Poor conductors as solid
Hard
Soluble in water
191
Why do ionic compounds have high fixed points?
(ionic bonds strong)
◆ Lots of energy required to overcome electrostatic attraction
192
Why are ionic compounds poor conductors as solids?
no moving/free electrons
193
Why are ionic compounds good conductors as liquids?
Conducts electricity as liquid (charged ions free to move)
194
When is a covalent bond formed?
when atoms share a pair of electrons
195
What is an covalent bond between?
Non-metals + Non-metals
196
What are molecules?
a group of atoms held together by COVALENT bonds
197
What are 3 properties of covalent compounds?
Low fixed points
Do not conduct electricity
Insoluble in water, but dissolve in organic solvents
198
Why don’t covalent compounds conduct electricity?
atoms not charged
199
Why do covalent compounds have low fixed points?
the weak intermolecular attractive forces
200
What are elements made out of?
Elements are made of tiny particles of matter called atoms
201
What are atoms made out of?
Each atom is made of subatomic particles called protons, neutrons and electrons
202
Why can’t we use conventional units e.g kg to compare the masses of atoms?
Their size is so tiny that we can’t really compare their masses in conventional units such as kilograms or grams
203
What unit is used to show the mass of an atom?
a unit called the relative atomic mass is used
204
What is one relative atomic mass unit equal to?
One relative atomic mass unit is equal to the mass of a carbon-12 atom.
205
Why does the relative atomic mass not have units?
All other elements are measured relative to the mass of a carbon-12 atom and since these are ratios, the relative atomic mass has no units
206
What is the relative mass of a proton?
1
207
What is the relative mass of a neutron?
1
208
What is the relative mass of an electron?
1/1840
209
What is the charge of a proton?
+1
210
What is the charge of a neutron?
0 (neutral)
211
What is the charge of an electron?
-1
212
What is the atomic number?
The atomic number (or proton number) is the number of protons in the nucleus of an atom.
213
What is the symbol for the atomic number?
Z
214
What does the atomic number also show? (apart from number of protons)
What does this determine?
It is also the number of electrons present in an atom and determines the position of the element on the Periodic Table
215
What is the nucleon number?
Nucleon number (or mass number) is the total number of protons and neutrons in the nucleus of an atom
216
What is the symbol for the nucleon number?
A
217
How can you calculate the number of neutrons using the nucleon and proton number?
The nucleon number minus the proton number gives you the number of neutrons of an atom
218
What are nucleons?
protons and neutrons can collectively be called nucleons.
219
What do electrons move around in?
They move in orbital paths called shells
220
Where is the mass of an atom contained and why?
The mass of the electron is negligible, hence the mass of an atom is contained within the nucleus where the neutron and proton reside
221
How are elements arranged on the periodic table?
Elements are arranged on the Periodic table in order of increasing atomic number where each element has one proton more than the element preceding it
222
What are the vertical columns in the periodic table called?
The table is arranged in vertical columns called Groups numbered I – VIII
223
What are the rows in the periodic table called?
Periods
224
What do elements in the same group have?
Elements in the same group have the same amount of electrons in their outer shell, which gives them similar chemical properties
225
Isotope definition
Isotopes are atoms of the same element that contain the same number of protons and electrons but a different number of neutrons.
226
What is the symbol for an isotope?
The symbol for an isotope is the chemical symbol (or word) followed by a dash and then the mass number.
227
Into what two categories can isotopes be divided?
radioactive and non-radioactive
228
Why are radioisotopes unstable?
Radioactive isotopes (radioisotopes) are unstable due to the imbalance of neutrons and protons
229
What does the imbalance of neutrons and protons in radioisotopes lead to?
causes the nucleus to decay over time through nuclear fission and emit radiation
230
What are examples of radioisotopes?
tritium and carbon-14
231
Does decay occur at the same rate for each isotope?
NO
Decay occurs at a different rate for each isotope
232
What is half-life?
the time taken for the radioactivity of an isotope to decrease by 50% is constant for that particular isotope and is known as the half-life
233
What are the properties of non-radioactive isotopes?
Non-radioactive isotopes are stable atoms which really only differ in their mass
234
What are the 3 medical uses for radioisotopes?
to treat cancer
medical tracers
to sterilise medical instruments
235
How are radioisotopes used to treat cancer?
Radiation is extremely harmful and kills cells so isotopes are used to treat cancer. The isotope cobalt-60 is frequently used for this purpose
236
How are radioisotopes used as medical tracers?
Medical tracers as certain parts of the body absorb isotopes and others do not. In this way an isotope can be injected into the blood and its path through the body traced with a radioactive detecting camera, revealing the flow of blood through bodily systems
237
How are radioisotopes used to sterilise medical equipment?
Medical instruments and materials are routinely sterilised by exposure to radiation, which kills any bacteria present
238
What are 3 industrial uses of radioisotopes?
radioactive dating
to detect leaks
to power power plants
239
How are radioisotopes used in radioactive dating?
Radioactive dating uses the carbon-14 isotope to date carbon-containing materials such as organic matter, rocks and other artefacts
240
How are radioisotopes used in detecting leaks?
Similar to medical use, radioactive tracers are deployed to detect leaks in gas or oil pipes
241
How are radioisotopes used to power power plants?
The radioactive isotope uranium-235 is used as nuclear in power plants in controlled fission reactions
242
Do isotopes of the same element display the same chemical characteristics?
Yes
243
Why do isotopes of the same element display the same chemical characteristics?
This is because they have the same number of electrons in their outer shells and this is what determines an atom’s chemistry
The difference between isotopes is the neutrons which are neutral particles within the nucleus and add mass only
244
How can we represent the structure of an atom?
using diagrams called electron shell diagrams
- by writing out a special notation called the electronic configuration
245
What is the correlation between the distance of the shell away from the nucleus and its energy?
The further away from the nucleus then the more energy a shell has.
246
What is the outermost shell called?
The outermost shell of an atom is called the valence shell
247
Why is it important for an atom to try and gain a full valence shell?
an atom is much more stable if it can manage to completely fill this shell with electrons
248
What does the last notation in the electronic configuration show?
The last notation shows the number of outer electrons the atom has, showing the Group that element is in
249
What do elements in the same group have in common?
Elements in the same Group have the same number of outer shell electrons
250
What property do all the noble gases share?
All of the noble gases are unreactive as they have full outer shells and are thus very stable
251
Element definition
A substance made of atoms that all contain the same number of protons (one type of atom) and cannot be split into anything simpler
252
Compound definition
A pure substance made up of two or more elements chemically combined
253
Can compounds be separated into their elements by physical means?
no
254
Mixture definition
A combination of two or more substances (elements and/or compounds) that are not chemically combined
255
Can mixtures be separated by physical methods?
YES
Mixtures can be separated by physical methods such as filtration or evaporation
256
What two broad types can elements be divided into?
They can be divided into two broad types: metals and nonmetals
257
What is a metalloid?
small number of elements display properties of both types (metal and non-metal)
258
What are the 6 key properties of metals?
Conduct heat and electricity
Are malleable and ductile (can be hammered and pulled into different shapes)
Tend to be lustrous (shiny)
Have high density and usually have high melting points
Form positive ions through electron loss
Form basic oxides
259
What are the 6 key properties of non-metals?
Do not conduct heat and electricity
Are brittle and delicate when solid and easily break up
Tend to be dull and non-reflective
Have low density and low melting points (many are gases at room temperature)
Form negative ions through electron gain (except for hydrogen)
Form acidic oxides
260
What are alloys?
Alloys are mixtures of metals, where the metals are mixed together but are not chemically combined
261
What can alloys be made out of?
They can be made from metals mixed with nonmetals such as carbon
262
Why are alloys preferable over pure metals?
Alloys often have properties that can be very different to the metals they contain, for example they can have more strength, hardness or resistance to corrosion or extreme temperatures
263
How are alloys stronger than pure metals?
Alloys contain atoms of different sizes, which distorts the regular arrangements of atoms
This makes it more difficult for the layers to slide over each other, so they are usually much harder than the pure metal
264
What is an example of an alloy?
Brass is a common example of an alloy which contains 70% copper and 30% zinc
265
Ion definition
An ion is an electrically charged atom or group of atoms formed by the loss or gain of electrons
266
Why do ions gain/loose electrons?
This loss or gain of electrons takes place to gain a full outer shell of electrons
267
What is the electronic structure of an ion the same as?
The electronic structure of an ion will be the same as that of a noble gas – such as helium, neon and argon
268
Do metals lose or gain electrons to form ions?
All metals lose electrons to other atoms to become positively charged ions
269
Do non-metals lose or gain electrons to form ions?
All non-metals gain electrons from other atoms to become negatively charged ions
270
How are ionic compounds held together?
The positive and negative charges are held together by the strong electrostatic forces of attraction between opposite charges.
271
What does the lattice structure refer to?
Lattice structure refers to the arrangement of the atoms of a substance in 3D space
272
How are atoms arranged in a lattice structure?
In lattice structures, the atoms are arranged in an ordered and repeating fashion
273
How is a lattice formed?
The lattices formed by ionic compounds consist of a regular arrangement of alternating positive and negative ions
274
How are covalent compounds formed?
Covalent compounds are formed when electrons are shared between atoms
275
What type of elements can participate in covalent bonding?
Only non-metal elements
276
What is similar between ionic and covalent bonding?
As in ionic bonding, each atom gains a full outer shell of electrons
277
What are molecules?
When two or more atoms are chemically bonded together, we describe them as ‘molecules’
278
Look at covalent compound diagrams 3.3
yes ;)
279
What is the difference in melting and boiling points in ionic and covalent compounds?
I - Have high melting and boiling points so ionic compounds are usually solid at room temperature
C - Have low melting and boiling points so covalent compounds are usually liquids or gases at room temperature
280
What is the difference in volatility in ionic and covalent compounds?
I - Not volatile so they don’t evaporate easily
C - Usually volatile which is why many covalent organic compounds have distinct aromas
281
What is the difference in water solubility in ionic and covalent compounds?
I - Usually water-soluble as both ionic compounds and water are polar
C - Usually not water-soluble as covalent compounds tend to be non-polar but can dissolve in organic solvents
282
What is the difference in ability to conduct electricity in ionic and covalent compounds?
I - Conduct electricity in molten state or in solution as they have ions that can move and carry a charge
C - Cannot conduct electricity as all electrons are involved in bonding so there are no free electrons or ions to carry the charge
283
Why do ionic compounds have high melting and boiling points?
This is because the oppositely charged ions in the lattice structure are attracted to each other by strong electrostatic forces which hold them firmly in place
Large amounts of energy are needed to overcome these forces so the m.p. and b.p. are high
284
Why do covalent compounds have lower melting and boiling points?
Simple covalent substances, such as carbon dioxide and methane, have very strong covalent bonds between the atoms in each molecule, but much weaker intermolecular forces between individual molecules
When one of these substances melts or boils, it is these weak intermolecular forces that break, not the strong covalent bonds
Less energy is needed to break the molecules apart, so they have lower m.p. and b.p. than ionic compounds
285
What is an allotrope?
Different atomic or molecular arrangements of the same element in the same physical state
286
What are diamond and graphite?
allotropes of carbon which have giant covalent structures
287
What do giant covalent structures look like?
This class of substances contains a lot of non-metal atoms, each joined to adjacent atoms by covalent bonds forming a giant lattice structure
288
Do giant covalent structures have high or low melting and boiling points? Why?
Giant covalent structures have HIGH melting and boiling points as they have many strong covalent bonds that need to be broken down
289
What is the structure of diamond?
Each carbon atom bonds with four other carbons, forming a tetrahedron
290
Describe the bonds in diamond
All the covalent bonds are identical and strong with no weak intermolecular forces
291
3 properties of diamond
Does not conduct electricity
Has a very high melting point
Is extremely hard and dense (3.51 g/cm3)
292
In what two ways can diamond be used?
Diamond is used in jewellery and as cutting tools
293
What is the structure of graphite?
Each carbon atom is bonded to three others forming layers of hexagonal-shaped forms, leaving one free electron per carbon atom
294
How can graphite conduct electricity?
These free electrons exist in between the layers and are free to move and carry charge, hence graphite can conduct electricity
295
Describe the bonds in graphite
The covalent bonds within the layers are very strong but the layers are connected to each other by weak intermolecular forces only, hence the layers can slide over each other making graphite slippery and smooth
296
3 properties of graphite
Conducts electricity
Has a very high melting point
Is soft and slippery, less dense than diamond (2.25 g/cm3)
297
What are 3 uses of graphite?
used in pencils
used s an industrial lubricant, in engines and in locks
used to make non-reactive electrodes for electrolysis
298
What type of compound is SiO2?
macromolecular compound
299
In what forms can SiO2 occur naturally?
sand and quartz
300
Describe the bonds in silicon dioxide
Each oxygen atom forms covalent bonds with 2 silicon atoms and each silicon atom in turn forms covalent bonds with 4 oxygen atoms
301
What shape is formed in the structure of SiO2?
A tetrahedron is formed with one silicon atom and four oxygen atoms, similar as in diamond
302
What giant covalent structure does SiO2 have similar properties to? Why?
SiO2 has lots of very strong covalent bonds and no intermolecular forces so it has similar properties to diamond
303
Properties of SiO2
It is very hard, has a very high boiling point, is insoluble in water and does not conduct electricity
304
What is SiO2 used for?
SiO2 is cheap since it is available naturally and is used to make sandpaper and to line the inside of furnaces
305
How are metal atoms held together?
Metal atoms are held together strongly by metallic bonding
306
How do metal ions become positively charged in a metallic lattice?
Within the metal lattice, the atoms lose their valence electrons and become positively charged
307
What are the electrons in a metallic lattice called and why?
The valence electrons no longer belong to any metal atom and are said to be delocalised
They move freely between the positive metal ions like a sea of electrons
308
Why are metallic bonds so strong?
Metallic bonds are strong and are a result of the attraction between the positive metal ions and the negatively charged delocalised electrons
309
What is the link between metallic bonding and the high melting and boiling points of metals?
There are many strong metallic bonds in giant metallic structures
A lot of heat energy is needed to overcome forces and break these bonds
310
What is the link between metallic bonding and the ability to conduct electricity of metals?
There are free electrons available to move and carry charge
Electrons entering one end of the metal cause a delocalised electron to displace itself from the other end
Hence electrons can flow so electricity is conducted
311
What is the link between metallic bonding and metals being malleable and ductile?
Layers of positive ions can slide over one another and take up different positions
Metallic bonding is not disrupted as the valence electrons do not belong to any particular metal atom so the delocalised electrons will move with them
Metallic bonds are thus not broken and as a result metals are strong but flexible
They can be hammered and bent into different shapes without breaking
312
Covalent Bonding vs Ionic Bonding
Sharing electrons vs transferring electrons.
313
Giant Ionic Lattice
A huge 3D network of ions, held together by electrostatic attraction (ionic bonding).
314
Group 1 Ionic Charge
1+
315
Group 2 Ionic Charge
2+
316
Group 3 Ionic Charge
3+
317
Group 4 Ionic Charge
Group 4 don’t form Ions.
318
Group 5 Ionic Charge
3-
319
Group 6 Ionic Charge
2-
320
Group 7 Ionic Charge
1-
321
Group 0 Ionic Charge
Group 0 never form ions.
322
Electrostatic Attraction
The force of attraction between positively and negatively charged ions. Act in all directions.
323
Giant Ionic Structure Facts.
Held together by strong electrostatic attraction.
Very high melting and boiling points because of this.
324
What happens when an ionic solid melts and becomes a liquid?
The ions are free to move anywhere in the liquid.
Attracted to oppositely charged electrodes dipped into the liquid.
Therefore, they carry their electrical charge through the liquid.
Conduct Electricity.
Water also separates many ionic solids and allows them to conduct electricity.The ions are free to move anywhere in the liquid.
Attracted to oppositely charged electrodes dipped into the liquid.
Therefore, they carry their electrical charge through the liquid.
Conduct Electricity.
Water also separates many ionic solids and allows them to conduct electricity.
325
Covalent Bonds
The bonds between two atoms that share one or more pairs of electrons.
326
Example of a Macromolecule.
Diamond.
Each carbon atom forms four covalent bonds with its neighbours.
This results in a rigid giant covalent lattice.
327
Covalent Bond Facts
Covalent bonds are very strong, so the two atoms it joins are very tightly bonded.
However, their intermolecular forces are very weak. Overcoming them is relatively easy and requires little energy.
328
Do covalently bonded substances conduct electricity?
No.
329
Giant Covalent Structures/ Macromolecules
STRONG covalent bonds
High melting and boiling points
Insoluble in water
Hard, do not conduct electricity (except for graphite)
330
Graphite
> Carbon atoms bond to three other carbon atoms.
Form hexagons which are arranged in giant layers.
Layers can slide over each other easily.
Graphite is soft and slippery- Easily malleable.
The fourth electron in Carbon’s outer shell becomes a DELOCALISED ELECTRON- These allow graphite to conduct electricity.
331
Fullerenes
Form of the element carbon that can exist as large cage-like structures, based on hexagonal rings of carbon atoms.
332
Nanoscience
The study of particles that are between 1 and 100 nanometres in size.
333
How do nanoparticles behave?
Differently to their larger scale counterparts.
334
What is the mass and charge of a proton?
Mass: 1 unit
Charge: +1
335
What is the mass and charge of a neutron?
Mass: 1 unit
Charge: no charge
336
What is the charge of an electron?
Charge: -1
337
What is the proton number/atomic number?
number of protons in nucleus of atom
338
What is the nucleon number?
number of protons and neutrons in the nucleus of an atom/relative atomic mass
339
What do columns in a periodic table show?
groups with similar reaction properties
340
What do rows in a periodic table show?
periods
341
What are isotopes?
atoms of same element with same proton number, different number of neutrons → different nucleon number
342
Why do isotopes have the same properties?
same properties because same number of electrons in outer shell
343
What are the two types of isotopes?
radioactive
non-radioactive
344
What are some medical and industrial uses for radioactive isotopes?
Medical: cancer treatment, locating tumours
Industrial: check for oil and gas leaks
345
What is oxidation state/valency number?
number of electrons in outer shell
346
Why is group 0 unreactive?
full outershell
347
Why do atoms with more electron shells have higher energy levels?
Further away from nucleus
348
What is an ion?
electrically charged particle
349
What is an ionic bond made of?
Metals + Non-metals
350
How are ionic bonds formed?
Atoms lose/gains electrons to become stable
351
What is the structure of ionic bonds?
arranged in a giant lattice with regular pattern of particles held together by strong ionic bonds
352
What are the properties of ionic compounds (5)?
High boiling + melting points (ionic bonds strong)
Poor conductors as solid (no free electrons/ions)
Conducts electricity as liquid
Hard
Soluble in water
353
Why do ionic compounds have high fixed points?
ionic bonds strong, lots of energy required to overcome electrostatic attraction
354
Why do ionic compounds conduct electricity as liquid?
charged ions free to move
355
What is a covalent bond made of?
Non-metal + Non-metal
356
What are molecules?
a group of atoms held together by COVALENT bonds
357
How are covalent bonds formed?
Atoms share pairs of electrons to achieve noble gas configuration
358
What is the strength of bonding in covalent bonds ?
Molecular bonds strong, intermolecular are weak
359
What are the properties of covalent compounds?
Low melting/boiling points
Don’t conduct electricity (not charged)
Insoluble in water, but dissolve in organic solvents
360
Why do covalent compounds have low fixed points?
weak intermolecular forces
361
How many electrons are shared in a single, double and triple covalent bond?
Single bond: 2 electrons shared (1 from each atom)
Double bond: 4 electrons shared (2 from each atom)
Triple bond: 6 electrons shared (3 from each atom)
362
Why do giant covalent structures have high fixed points?
structure made up of strong covalent bonds
363
Why don’t giant covalent structures conduct electricity?
have no mobile ions or electrons, except for graphite
364
What are the properties of diamond? (4)
Shares 4 valence electrons → 3D lattice
Strong covalent bonds
High fixed points
Forms tetrahedron
365
What are the properties of graphite? (6)
Shares 3 valence electrons
4th electron free – Free moving electrons
Strong covalent bonds
Held together by weak forces so is soft and slippery -used as a lubricant
Slide over each other
366
What are the properties of silicon dioxide? (5)
Makes up sand
Each Si is bonded to 4 oxygen atoms
Each oxygen bonded to 2 silicon atoms
High fixed points
Hard
367
What are delocalized electrons
Free electrons in metallic bonding
368
Why can metals conduct electricity and heat?
Delocalized electrons can carry charge
369
Why are metals malleable + ductile?
attractive forces between metal ions and electrons act in any direction – when layers slide new bonds can easily form
370
Between what are ionic compounds formed?
no metals and metals
371
Between what are covalent compounds formed?
non metals and non metals
372
How are carbon atoms in diamond formed?
A carbon atoms forms covalent bonds to 4 others
373
What are the diamond properties?
hardest known substance
does not conduct electricity
sparkles when cut
374
What are graphite properties?
soft and slippery
soft and dark in colour
conducts electricity
375
Describe properties of ionic compounds
the ions are an ionic lattice and are held together by strong electrostatic forces
they are hard
they are solids
they are brittle
they are insulators
376
Why are ionic compounds insulators?
bc the strong electrostatic forces hold the ions in one place
377
What happens when an ionic compounds are molten or dissolved in water?
the ions are free to move around so they can conduct electricity
378
What are properties of covalent molecules?
they are solids
they are hard
they are malleable or ductile
not conduct electricity
not dissolve in water
379
Describe the forces between covalent molecules
they are very weak
380
How does this affect the rest?
if it is a gas it has low boiling and melting point
not conduct electricity
not dissolve water
381
what is intermolecular?
weak forces between molecules so it is a gas
382
What is intramolecular?
strong forces between covalent molecules
383
What are key points of metallic bonding?
in metallic bonds atoms lose their outer electrons
the lattice of metal ions are in a sea of shared electrons
the electrostatic force between metal ions and delocalised electrons are strong
384
What are properties of metals?
metals are solids
metals are malleable and ductile
metals conduct electricity and heat
385
Why are metals solids?
They are solids because the electrostatic forces between metal ions and the delocalised electrons are strong
386
Why are metals malleable and ductile?
metal ions can slide over one another in the sea of electrons
387
Why can metals conduct electricity and heat?
the shared electrons are free to move within the sea of electrons
388
What are the 3 states of matter?
solid, liquid and gas
389
state the properties of a solid
fixed vol and shape
high density
atoms vibrate in position but can’t change location
atoms packed very closely together and in a fixed position
390
state properties of a liquid
fixed vol but can adapt shape of a container
less dense than solids but much denser than gases
density is medium
particles move and slide past eachother= this is how they adopt the shape of a container
391
state properties of a gas
no fixed vol and adapt shape of a container
low density
can be compressed into a much smaller volume due to the spaces in between particles
particles are futher apart and move quickly causing collusions
they collide with eachother
392
How strong the forces are between particles depend on what?
the material
the temp
the pressure
393
What is melting?
solid changing into a liquid
requires heat energy in which transforms into KINESTIC energy so that particles are allowed to move
happens in a specific temp- melting point
394
what is boiling?
liquid to gas
requires heat which causes bubbles of gas found below the surface of the liquid
occurs at a specific temp- boiling point
395
what is freezing?
liquid to solid
reverse of melting and happens at the same temp as melting because THE MELTING AND FREEZING POINT OF A PURE SUBSTANCE IS THE SAME
required loss of thermal energy
happens in a specific temp
396
What is evapouration?
liquid to gas
happens in a range of temperatures
397
when does eveporation only occur?
in the surface of a liquid where high energy particles can escape
398
the larger the what in evaporation the quicklier?
the larger the surface area and the warmer the surface of the liquid surface
399
What is condensation?
gas into a liquid
takes place in range of temperature
400
explain condensation with the theory of particles
as gas is cooled, particles begin to loose more energy= when they collide with eachother they lack energy to bounce again, instead they come together and form a liquid
401
what is the kinetic theory of matter?
when substances are heated, particles absorb the thermal energy which is then converted into kinetic energy
402
what does a heating curve demonstrate?
demonstrates states and state changes aswell as time progresses
403
What are the effects of temperature and pressure
on the volume of a gas
as temperature increases, gas volume increases
density increases as volume increases
404
Give two examples to demonstrate the effects of temperature and pressure on the volume of a gas
A hot air ballon: as air inside the ballon is heated, it expands and ballon gets bigger and as density decreases, the more up it’ll go
gas syringe covered with a finger you compress it and there will be a point where yo can’t anymore bcs there’s air
405
Explain, in terms of kinetic particle theory, the
effects of temperature and pressure on the
volume of a gas
increase of temperature means an increase of kinetic energy of each particle, and as the heat is transformed into kinetic energy, they move faster
decrease in volume=increase of pressure
406
gaseous particles are..
constant and in random motion
407
How is the pressure that gas created inside a closed container created
by gaseous particles hitting the inside walls of the container
408
What happens when there is a decrease in volume in a gas container
it increases the pressure
409
Describe and explain diffusion in terms of kinetic
particle theory
Diffusing particles move from an area of high concentration to an area of low concentration, eventually leading to an equilibrium since concentration of particles spread evenly out to occupy available space
410
Does diffusion use kinetic energy/ any type of energy? Is there any input energy required too? Explain
Happens on it’s own and no energy input is required ALTHOUGH diffusion takes place in a higher rate in higher temperatures
411
Describe and explain the effect of relative
molecular mass on the rate of diffusion of gases
the lighter the relative mass= the faster the rate of diffusion will happen
412
Give an example of an experiment where diffusion is seen
Potassium Magnate (VII) and water
beaker of water and place potassium magnate (VII) at the bottom, you will remark that purple will start to spread out among particles of water.
RANDOM MOTION of particles causes the evenly spread of particles to happen.
413
Does diffusion occur faster in gases or liquids? Why
Gases because the particles move much quicker than liquid particles
414
Why do gases not diffuse at the same rate in the same temperature? Give an example
This is due to the difference in their relative atomic masses
Lighter gas particles move faster and hence further just because they have lower relative mass so they will diffuse faster
Ammonia gas in Hydrogen chloride gas inside a long glass tube
NH3 and HCL
Where the two gases meet the white ring will form, it will actually form nearest to the end with HCL because the Mr of ammonia is 17 and HCL is 36.5 meaning that NH3 is much lighter so diffusion rate is faster.
415
What happens when you add more water to a solution with Potassium magnate (VII) which has already diffused in the beaker evenly?
Particles of Potassium magnate will spread even further apart and solution will become less purple. =Dilute
416
Define an element
substance made up of atoms that that all contain the same amount of protons
substance that can no longer be divided
417
Define a mixture
combination of two or more substances that are NOT chemically combined
Mixtures can be seperated by physical methods
418
Define a compound
pure substance of two or more elements chemically combined
they can’t be seperated back to their orginal elements by physical means
419
Difference between mixture and compound
mixture isn’t chemically combined and physical methods can be used to separate the elements inside whereas in the compound the elements are chemically combined and it’s not possible to separate them by physical means.
Compounds also have a sharp and specific bp and mp whereas mixtures will boil in a range of temperatures
420
a substance is pure if…
it has a sharp, specific boiling point, and melting point
if it is completely made up of a single element or a compound
421
What are the subatomic particles of an atom
electron
proton
neutron
422
Describe the structure of the atom
central nucleus containing neutrons and protons
surrounded by electrons in shells
423
What subatoms are located in the nucleus of an atom?
Protons and neutrons
424
What subatom is found in the shells of an element
electrons
425
What is the relative atomic mass of a proton
1
426
What is the relative atomic mass of a neutron
1
427
What is the relative atomic mass of an electron
0.005
428
Define proton number/ atomic number
number of protons in the nucleus of an atom
429
Define mass number/nucleon number
total number of protons and neutrons in the
nucleus of an atom
430
number of outer shell electrons is equal
to…?
the group number in Groups I to VII
431
the number of occupied electron shells is equal to…?
equal to the period number
432
What is the relative charge of a proton
+1
433
What is the relative charge of a neutron
0
434
What is the relative charge of an electron
-1
435
Number of protons in an element equal to what?
number of electrons
436
How can you calculate the number of neutrons in an element?
nucleon/mass number MINUS proton number
437
EASY TIP!!!!
MASS= MASSIVE, mass number is ALWYAS the bigger one
438
How to calculate the mass number of an element?
number of neutrons+ number of protons
439
What determines which element one is?
the atomic number of an atom and ion
440
maximum capacity of electrons the first shell can hold
2
441
maximum capacity of electrons the second shell can hold
8
442
maximum capacity of electrons the third shell can hold
8
443
Define the term isotope
different atoms of the same
element that have the same number of protons
but different numbers of neutrons
444
What is an ion?
ELECTRICALLY CHARGED atom or group of atoms formed by the loss or gains of electrons
445
Do isotopes of the same element have the same chemical properties?
isotopes of the same element have
the same chemical properties because they have
the same number of electrons and therefore the
same electronic configuration
446
Where does the loss or gain of electrons take place in?
outer most shell
447
Explain the ionisation of metals or formation of cations
all metals can loose electrons to other atoms to become positive ions known as CATIONS
448
Explain the ionisation of non-metals or formation of cations
all non metals can gain electrons from other atoms to become negatively charged ions, known as ANIONS
449
State what an ionic bond is
a strong electrostatic attraction between oppositely charged ions that keep ionic compounds together
450
How are ionic compounds formed? Explain
when metals react with non-metals
Metals loose one of their outermost electrons and non-metals GAIN to form positive and negative ions
451
What are positive and negative ions hold together by?
electrostatic forces of attractions between opposite charges
452
Describe the giant lattice structure of ionic
compounds
regular arrangement of alternating positive and negative ions
453
How is the lattice structure of ionic compounds?
GIANT, has regular arrangement of alternating positive and negative ions
454
What is formed when when metal atoms and non-metal atoms react?
Ionic compounds
455
Describe the properties of ionic compounds:
high melting points and boiling points
good electrical conductivity when aqueous or
molten and poor when solid
good conductors of electricity in molten state or in a solution
456
Explain in terms of structure and bonding the
properties of ionic compounds:
they have high melting/boiling points due to presence of strong electrostatic forces acting between oppositely charged ions =forces act in all directs and are very hard to overcome them
457
The greater the charge of ions means…
the greater the electrostatic forces will be and the higher the mp and bp will be
458
What is requires for electrical currents to flow?
freely moving charged particles such as ions or electrons present
459
In what state do ionic compounds conduct electricity the best?
molten or in a solution as they have ions that can move and carry a charge
460
When is a convalent bond formed?
when a pair of electrons is shared between two atoms leading
to noble gas electronic configurations
461
What is the difference between ionic bonding and convalent bonding?
in covalent bonding the forces are quite weak whereas in ionic theyre the strongest type of chemical bond
metallic elements tend to form ionic bonds whilst non metallic elements tend to form covalent bonds
in ionic bonding it’s the attraction of eletrosatic forces of attraction of oppositely charged ions and in covalent the interaction of atoms are neutral and have no charge which makes them weaker
462
Who can only participate in convalent bonding?
non metals
463
When two or more atoms are contently bonded we describe them as…?
molecules
464
How is a double bond formed
two adjacent atoms sharing a pair of electrons, two convalent bonds are formed=double bond formed
465
How is a triple bond formed
two adjacent atoms sharing 3 pairs of electrons, three convalent bonds are formed=triple bond formed
466
State the properties of simple molecular compounds
poor electrical conductivity
low melting points and boiling points due to weak intermolecular forces
467
Describe diamond’s covalent structure?
each carbon atom bonds with 4 other carbons, forming a TETRAHEDRON
all covalent bonds are identical, very strong and there are no intermolecular forces
468
Describe the giant covalent structures of graphite
and diamond
both substances contain only carbon atoms (due to the differences in bonding arrangements they are physically different)
469
Describe the giant covalent structure of
silicon(IV) oxide, SiO2
it is a macromolecular compound which occurs NATURALLY as sand and quartz
oxygen atom forms covalent bond with 2 silicon atoms and each silicon atom in turn forms covalent bonds wit 4 oxygen atoms
has lots of very strong intermolecular forces
very hard
very high melting point
insoluble in water
doesn’t conduct electricity
cheap since it available naturally
used to make sand paper
470
Describe the similarity in properties between
diamond and silicon(IV) oxide, related to their
structures
very high melting points due to regular repeating lattice and strong covalent bonds
don’t conduct electricity even when molten
strong
471
What is diamond used for?
cutting tools
472
What is graphite used for?
a lubricant and as an electrode
473
What is metallic bonding?
e electrostatic attraction between the positive ions in a giant
metallic lattice and a ‘sea’ of delocalised
electrons
474
Why do metals have good electrical conductivity, are malleable and ductile?
Because of strong metallic bonding
delocalization of electrons in metallic bonds confers to the electrical conductivity
layers of positive ions can slide over one another and take up different positions
475
malleable definition
capable of being hammered out into a sheet
476
ductile definition
capable of being drawn into a wire
477
What is a giant covalent structure?
solids with very high melting points
all atoms are linked by strong covalent bonds which must be broken to melt the substance
478
Describe the covalent structure of Graphite?
Each carbon atoms in graphite is bonded to three others forming layers of hexagons, leaving 1 free electron per carbon which becomes delocalized
covalent bonds within layers are very strong, but layers are attracted to each other by weak intermolecular forces
479
properties of a diamond
doesn’t conduct electricity
very high melting point
it is extremly hard and dense
there are no freely moving charged particles to carry the current so it can’t conduct electricity
hard but brittle
480
what is diamond used for?
jewlery for shiny appearance and for cutting tools since it is such hard material
481
properties of graphite
conducts electricity
has a very high melting point
soft and slippery
less dense than diamond
482
what is graphite used for?
pencils and industrial lubricant
lock
engines
used to make non-reactive elctrodes for electrolysis
483
why do metals conduct electricity?
because of the free electrons available to move
electrons can flow= electricity is conducted
484
Define an allatrope:
different structural forms of the same element in the same physical state
485
what is an ionic bond
attraction of positive and negative ions
486
why do ionic compounds have high melting points?
due to the large number of strong electrostatic attractions between the positive and neative ions
(due to strong ionoic bonding)
487
what does covalent bonding consist of?
one or more shared pairs of electrons between two atoms
488
what are delocalized electrons?
electrons that can move about between layers and are not bound to an individual atom
489
what is a metallic bond?
electrostatic attraction between delocalised electrons and the positive metal ions in the lattice
490
how can metals be so ductile and malleable
because of the layered structurz of the lattice - which cab slide over eachother without breaking the bonds
491
how is the structure of macromolecular substances described as?
giant
macromolecular
492
what does the molecular formula actually show?
actual number if atoms each ekement in a compound has
493
what does the structural formulae show?
shows arrangement of atoms
494
what is an alloy?
mixture containing a metal and another element (non metal or metal)
495
How many outer electrons does magnesium have?
Which group is magnesium found in?
How many electron shells does magnesium have?
What period is it found in?
2 outer electrons
Group 2 - called the Earth Alkaline metals
3 electron shells
Period 3
496
What does the group number in the periodic table represents?
The number of outer electrons
497
What is the electronic configuration of helium-4 with a proton number of 2.
2 in the first shell
4 is the mass number, since it is neutral it will have 2 electrons to equal the number of protons (+2) + (-2) = 0
498
Why is group 0 or the noble gases inert (unreactive)?
They have a full outer shell
499
Name the subatomic particles which are also nucleons.
proton and neutrons because they are found in the nucleus
500
To which group and period does this element belong?
Chlorine-35
Chlorine has a proton number of 17
The proton number is 17 therefore it has 17 electrons.
The electronic configuration is
2,8,7
group 7 - it has 7 outer electrons
period 3 - it has 3 electron shells
501
Which two ions have an electronic configuration of 2,8,8?
Cl 1- and K 1+
Chlorine is 2,8,7 and gains one electron to become 2,8,8 and gains a charge of 1-
Potassium is 2,8,8,1 and losed one electron to become 2,8,8 and gains a charge of 1+
502
What subatomic particles are found in the nucleus?
protons and neutrons
503
Naturally occurring chlorine consists of atoms of relative masses 35 (75%) and 37 (25%). Without calculating which RAM is more likely and why? 37.5, 35.5. or 36.0
35.5 because the number is closest to 35 which has a greater abundance of 75%.
504
Define relative atomic mass (RAM)
The average mass number of an atom relative to 1/12th the mass of Carbon-12 taking into consideration the abundance of all its isotopes.
505
Which element has 8 outer electrons?
Ne-10 proton number 8
OR O-16 proton number 8
Neon - its electronic configuration is 2,8
Neon has 10 electrons but 8 outer electrons
506
What is the charge of a proton, neutron and electron respectively?
proton 1+, neutron 0, electron 1-
507
How do you find the number of neutrons found in Na-23 which has a proton number of 11.
mass number - proton number = number of neutrons 23 - 11 = 12 neutrons
508
What is the electronic configuration of N3-
Nirogen has a proton number of 7.
2,8
Nitrogen is 2,5 but it has gained 3 electrons to give N 3-
509
What does the period number represent in the periodic table?
The number of electron shells
510
How many outer electrons does aluminium have?
Which group is aluminium found in?
How many electron shells does aluminium have?
What period is it found in?
3 outer electrons
Group 3
3 electron shells
Period 3
511
What is the electronic configuration of oxygen-16 with a proton number of 8?
2,6
Check:
oxygen is in group 6 and should have 6 outer electrons
oxygen is in period 2 and should have 2 electron shells
512
What is the electronic configuration of potassium-39 with a proton number of 19?
How would this change when its ion is formed?
2,8,8,1
it would become
2,8,8
having lost its outer electron to gain a full outer shell and become more stable
513
Which element has 10 neutrons?
F-19 proton number 9
Ne-20 proton number 10
B-10 proton number 5
Fluorine
19 - 9 = 10 neutrons
514
What is the electronic configuration of F 1-
Fluroine has a proton number of 9.
2,8
Fluorine is 2,7 but has gained one electron to make F 1-
515
What is the mass number of Lithium-7 which has 3 protons?
7
516
What is the electronic configuration of hydrogen-1 with a proton number of 1.
1
517
These are the same element, they have the same number of protons but have different number of neutrons. What are they?
They are isotopes
518
How is a negative ion formed?
A neutral atom gains electrons
519
What is the octet rule?
Atoms gain or lose electrons to obtain a full outer shell which makes the atom more stable.
520
Which element will form an ion with charge 3-
Nitrogen found in group 3
Aluminium with 3 outer electrons
sodium found in period 3
Nitrogen, its electronic configuration is 2,5 so it gains 3 electrons to become 2,8 with a charge of 3-
521
How is a positive ion formed?
The neutral atom must lose electrons.
522
What is the electronic configuration of Sulfur-32 which has a proton number of 16.
2,8,6
523
What is the relative mass of a proton, neutrons and electron?
proton 1, neutron 1 - same relative mass
electron (0 or 1/1840)- more of less zero
524
Which charge ion will this element form?
Chlorine with electronic configuration 2,8,7
It has 7 outer electrons- it will gain one electron and will have the charge 1-
525
What is the electronic configuration of sodium-23 with a proton number of 11.
2,8,1
Check your answer:
Na is is group 1 and should have 1 outer electron
526
Which ions can have the electronic configuration
2,8
F 1- and Na 1+
Fluorine is 2,7 but gains one to become 2,8
with a charge of 1-
sodium is 2,8,1 but loses one electron to become 2,8
with a charge of 1+
527
What is the mass number of an atom?
mass number = number of protons + number of neutrons
528
What is the electronic configuration of Ca 2+
Calcium has a proton number of 20.
2,8,8
Ca is 2,8,8,2 but Ca 2+ has lost its two outer electrons to gain a full outer shell.
529
How many neutrons does lithium-7 have?
Lithium has 3 protons
7-3 = 4 neutrons
530
How many outer electrons does chlorine have?
Which group is chlorine found in?
What is the name of this group?
7 outer electrons
Group 7
Halogens
531
How do the chemical properties of isotopes compare?
Isotopes have similar chemical properties because they have the same number of outer electrons.
C-12 and C-14 both have 6 protons and 6 electrons but C-14 has 2 more neutrons and is therefore slightly heavier. But they both have 4 outer electrons and behave the same chemically
532
What is the electronic configuration of chlorine-35 with a proton number of 17?
2,8,7
Check:
Chlorine is in group 7 and should have 7 outer electrons
Chlorine is in period 3 and should have 3 electron shells
533
What is an isotope?
An atom of the same element with same number of protons and different number of neutrons
534
Substances can be found in three states. Name them.
Substances can be solids, liquids or gases.
535
What is all matter made of of?
All matter is made up of particles.
536
Three types of particles make up most matter - Name them.
Three types of particles make up most matter - atoms, molecules and ions.
537
What is an atom?
An atom is the smallest particle that cannot be broken down by chemical means.
538
What is a molecule?
A molecule is a particle of two or more atoms joined together.
539
What is an ion?
An ion is an atom or group of atoms that carries an electrical charge.
540
What is the shape, volume, and density of a solid-like, and can it flow?
Definite shape and volume.
High density.
Cannot flow.
541
What is the shape, volume, and density of a liquid-like, and can it flow?
Definite volume.
Takes the shape of the container.
Moderate to high density.
Can flow.
542
What are the shape, volume, and density of a gas-like?
No definite volume.
Spreads everywhere throughout its container.
Low density.
543
Answer the following about solids:
- Attractive forces.
- Arrangement.
- Motion.
- Proximity.
Strong forces of attraction between particles.
Fixed and regular pattern.
Atoms vibrate in position.
Packed closely together.
544
Answer the following about liquid:
- Attractive forces.
- Arrangement.
- Motion.
- Proximity.
Weaker attractive forces in liquids than in solids.
Irregular, unfixed pattern.
Particles can move and slide past each other.
Particles are close together.
545
Answer the following about gases:
- Attractive forces.
- Arrangement.
- Motion.
- Proximity.
No attractive forces.
Particles move everywhere rapidly.
Particles are in random movement.
Particles are far apart.
546
State the compressibility of the following:
- Solids.
- Liquids.
- Gases.
Not compressible.
Not compressible.
Compressible.
547
What is melting?
Melting is when a solid changes into a liquid at a constant temperature.
548
What energy does melting require and what does it transform into?
Requires heat energy which transforms into kinetic energy, allowing the particles to move.
549
What temperature does melting occur at?
Occurs at a specific temperature known as the melting point.
550
What is boiling?
Boiling is when a liquid changes into a gas at a constant temperature.
551
What does boiling require and what does it form?
Requires heat which causes bubbles of gas to form below the surface of a liquid, allowing for liquid particles to escape from the surface and within the liquid.
552
What temperature does boiling occur at?
Occurs at a specific temperature known as the boiling point.
553
What is freezing?
Freezing is when a liquid changes into a solid.
554
What does freezing require?
Requires a significant decrease in temperature (or loss of thermal energy).
555
Define evaporation.
When a liquid changes into a gas.
556
Where does evaporation occur? Explain your answer.
Evaporation occurs only at the surface of liquids where high-energy particles can escape from the liquid’s surface at low temperatures, below the b.p. of the liquid.
557
How can evaporation be sped up?
The larger the surface area and the warmer the liquid/surface, the more quickly a liquid can evaporate.
558
What is sublimation?
When a solid changes directly into a gas.
559
What is condensation?
When a gas changes into a liquid, usually on cooling. .
560
Explain how condensation occurs.
When a gas is cooled its particles lose energy and when they bump into each other they lack the energy to bounce away again, instead they group together to form a liquid.
561
What happens to energy when a substance freezes or condenses.
Energy is given out to the surrounding (exothermic reaction) when a substance condenses or freezes.
562
What happens to energy when a substance melts or boils?
Energy must be put in (endothermic reaction) to melt and boil a substance.
563
What happens when you heat the gas in a closed container?
As the temperature increases, the particles in the gas move faster, impacting the container’s walls more frequently with increased force..
564
When a gas is heated in a closed container, the gas particles hit the walls of the container with increased force. Why?
The higher the temperature, the higher the pressure will be in the container (pressure is caused by the gaseous particles hitting the inside walls of the container).
565
Evidence for the kinetic theory?
Brownian motion and diffusion.
566
Define diffusion.
This is the process by which different gases or different liquids mix and is due to the random motion of their particles.
567
In what direction do diffusing particles move?
Diffusing particles move from an area of high concentration to an area of low concentration.
568
Diffusion in gases is faster than in liquids. Why is this?
Diffusion occurs much faster in gases than in liquids as gaseous particles move much quicker than liquid particles.
569
What happens with molecules with a lower molecular mass regarding the speed of diffusion?
Molecules that have a lower mass move faster than those with a higher mass.
570
At the same temperature, different gases do not diffuse at the same rate. Why?
This is due to the difference in their relative molecular masses.
571
What does heating a solid do?
Heating a solid causes its particles to vibrate more and as the temperature increases, they vibrate so much that the solid expands until the structure breaks and the solid melts.
572
What does heating a liquid do?
Heating the liquid expands it more and some particles at the surface gain sufficient energy to overcome the attractive forces and evaporate.
573
What happens when the b.p. temperature is reached for a liquid?
When the b.p. temperature is reached, all the particles gain enough energy to escape and the liquids boils.
574
What happens when you compress gases or decrease the volume of the container?
When the volume of the container is decreased, the gas molecules are squashed closer together and hit the walls of the container more often.
575
What happens when you heat the gas in a closed container but the volume of the gas is not fixed?
If the volume of the gas is not fixed, the volume of gas increases as the temperature increases.
576
What is the kinetic particle theory?
The idea that particles are constantly in motion is called the kinetic particle theory.
577
What four things do the kinetic particle theory state:
Particles in gases and liquid move randomly.
Particles in gases do not attract each other.
Particles in gases are so tiny that their volume can be ignored.
When the particles in gases collide they bounce off each other without any overall energy change.
578
What happens if the light and heavy molecules have the same amount of energy when they collide?
If the light and heavy molecules have the same amount of energy when they collide, the lighter ones will bounce off the heavier ones quicker.
579
What does the kinetic particles model state?
The kinetic particle model states that the particles in liquids and gases are in constant motion and that when the particles in gases collide they bounce off each other.
580
Why is the rate of diffusion slower in liquids than in gases?
The rate of diffusion is slower in liquids than in gases because there are weak attractive forces between the liquid particles.
581
Why does diffusion occur in gases?
Diffusion occurs in gases because the molecules in gases are constantly moving, colliding with each other and changing directions. Resulting in the gases spreading out.
582
What does the rate of diffusion depend on?
The rate of diffusion depends on the relative molecular mass.
583
Fill in the missing answers:
Substances with a _____ relative molecular ____ diffuse more slowly than those with a ____ relative ______ mass.
Substances with a higher relative molecular mass diffuse more slowly than those with a lower relative molecular mass.
584
Evidence for the Brownian motion?
Evidence for the Brownian Motion comes from the observations of the motion of tiny visible particles suspended in liquids and gases.
585
Larger heavier particles do not show Brownian Motion. Why is this?
This is because the differences in force of the collisions of molecules on each side of the heavier particles is not large enough to move them.
586
Diagrams to revise:
Cooling Curve and Heating Curve, Brownian Motion.
587
What is the temperature of room temperature?
Generally taken as about 20°C.
588
What is the order of a heating curve?
solid heating up - solid melting - liquid heating up - liquid vaporizing - gas heating up.
589
What is an atom?
The smallest part of an element that can take part in a chemical change.
590
Each atom is made up of subatomic particles. Name them.
Each atom is made of subatomic particles called protons, neutrons and electrons.
591
What are protons?
A proton is a positively charged particle found in the nucleus of an atom.
592
What is a neutron?
A neutron is a subatomic particle with no charge and is found in the nucleus of an atom.
593
A neutron is a subatomic particle with no charge and is found in the nucleus of an atom.
An electron is a negatively charged particle found orbiting in the shell around a nucleus.
594
What can collectively be called nucleons?
Protons and neutrons can collectively be called nucleons.
595
Why is it correct to say that an atom is an electrically neutral entity?
An atom is an electrically neutral entity because they contain equal quantities of positively charged protons and negatively charged electrons.
596
State the relative charge and approximate relative mass for a proton.
Relative charge of a proton = +1.
Approximate relative mass of a proton = 1.
597
State the relativle charge and approximate relative mass for a neutron.
Relative charge of a neutron = 0 (neutral).
Approximate relative mass of a neutron = 1.
598
State the relative charge and approximate relative mass for an electron.
Relative charge of an electron = -1.
Approximate relative mass of an electron = 1/1840.
599
Define proton number (atomic number).
The proton number (or atomic number) is the number of protons in the nucleus of an atom.
600
Define nucleon number (mass number).
Nucleon number (or mass number) is the total number of protons and neutrons in the nucleus of an atom.
601
What is an element?
A substance containing only one type of atom and cannot be split into anything simpler.
For example sodium, chlorine, and argon.
602
How are elements in the same periodic group similar?
Elements in the same periodic group have the same amount of electrons in their
outer shell, which gives them similar chemical properties.
603
How are elements arranged in Periods?
Elements are arranged in order of increasing atomic number (proton number), in rows called
periods.
604
Fill in the missing spaces :
The number of _____ or _____ _____ is the same as the period number.
Elements in the same Group have the same ______ of outer shell ________.
The number of shells or energy levels is the same as the period number.
Elements in the same Group have the same number of outer shell electrons.
605
What is a compound?
A substance containing two or more types of atoms chemically combined.
For example sulfur dioxide, sulfuric acid, and magnesium oxide.
NOTE - The formation of a compound is irreversible.
606
What is a mixture?
Two or more substances mixed together but not chemically combined.
607
Define Isotopes.
Isotopes are atoms of the same element that contain the same number of protons and electrons but a different number of neutrons.
608
What are the two types of isotopes?
Isotopes can be divided into two types: radioactive and non-radioactive.
609
Give 1 MEDICAL uses of radioisotopes.
Medical :
Medical instruments and materials are routinely sterilized by exposure to radiation.
Radiation is extremely harmful and kills cells, radioisotopes are used to treat cancer.
610
Give 1 INDUSTRIAL use of radioisotopes.
Industrial:
Radioactive tracers called a Geiger counter is deployed to detect leaks in gas or oil pipes.
611
Why do isotopes have the same properties?
Isotopes have the same chemical properties because they have the same number of electrons in their outer shell and the number of electrons in the outer shell is responsible for chemical reactions and they also have the same number of protons so are still classed as the same element.
612
Radioisotopes or radioactive isotopes are unstable, why?
Radioactive isotopes (radioisotopes) are unstable due to the imbalance of neutrons and protons, which causes the nucleus to decay over time.
613
What are noble gases/group 8/ group 0 elements?
Nobles gases have 8 electrons in their outer shells already (except helium, which has 2), making them very stable and unreactive.
614
How are electrons arranged?
Electrons are arranged around the nucleus in shells:
o First shell can have up to 2 electrons
o Second shell can have up to 8 electrons
o Third shell can have up to 8 electrons
615
When reacting, why will all atoms try to acquire 8 electrons in the outer shell/the maximum number of electrons in the outer shell?
NOTE - Another name for the outer shell of an atom is the valence shell.
When reacting, all atoms try to acquire the maximum number of electrons in the outer shell because this is the most stable arrangement.
616
Name this complex ion and give its valency
NH4
ammonium ion
valency 1+
617
This is the CO3 complex ion. State its name and valency
Carbonate ion
valency 2-
618
What is the valency of a zinc ion?
Zn 2+
619
What is the formula of calcium fluoride?
CaF2
Ca is in group 2 - has valency of 2+
F is in group 7 - has valency of 1-
Use cross and drop….
620
What is the formula of magnesium oxide?
MgO
Mg is in group 2 - has valency of 2+
O is in group 2 - has valency of 2-
Use cross and drop…. anc cancel down to simplest ratio
621
Explain in terms of electrons how Na and O react to form sodium oxide
Two Na ions lose one electron each to form 2 Na+ ions
One oxygen atom gain these 2 electrons to form O2-
2[Na+] O2-
Na2O
622
Why do both metals and molten ionic compounds conduct electricity?
Both have charge particles which are free to move and carry charge
But, metals have negatively charge electrons which can carry charge and molten ionic compound have both postive and negative ions which can carry charge.
623
What are the two possible copper ions?
Cu 1+ and Cu 2+
624
Draw a cross dot diagram from Magnesium fluoride
remeber to use square brackets and to write in the charge of the ions
625
Calcium loses two electrons to become Ca2+.
Is calcium oxidised or reduced?
oxidised
OIL RIG
Oxidation is loss of electrons
626
Draw the dot cross diagram for sodium oxide
remeber to use square brackets and to write in the charge of the ions
627
Draw the structure of an ionic compound
Alternating + and - ions in a giant (3D) lattice structure
628
Explain in terms of electrons how Mg and Cl react to form Magnesium chloride
Mg loses 2 electrons to form Mg2+
Two Cl atoms gain one electron each to form two Cl- ions
Mg2+ 2 [Cl1-]
629
Why is an ionic compound soluble in water but not soluble in an organic solvent?
Ionic compounds consist of charged ions and water molecules are polar (have charged ends on the molecule) this forms electrostatic attraction which can pull ionic compounds apart making them dissolve or dissociate
organic solvents do not have polar molecules (or molecules with charged ends) so they cannot attract and pull apart the ions in ionic compounds.
630
Draw a dot cross diagram for Magnesium oxide
remeber to use square brackets and to write in the charge of the ions
631
Draw a dot cross diagram for Magnesium oxide
632
What is the valency of the hydroxide ion
OH 1-
633
What is oxidation?
When an atom loses electrons OR gains oxygen
K1+ - potassium lost one electron
MgO - magnsium has gained oxygen
634
What is the formula of sodium nitride?
Na3N
Na is in group 1 - has valency of 1+
N is in group 5 - has valency of 3-
Use cross and drop….
635
Describe how electron shielding makes elements like potassium more reactive than lithium.
Potassium is a large atom
Potassium has more electrons (more electron shielding) between the nucleus and outer electrons and therefore has more repulsion on the outer electrons
The outer electron in potassium requires less energy to be remove
Therefore potassium is more reactive than lithium
636
Why is the melting point of MgO higher than the melting point of NaCl?
Mg ion has a charge of 2+ and oxygen ion has a charge of 2-
Na ion has a charge of 1+ and chloride ion has a charge of 1-
The ions in MgO have double the charge and therefore have a much greater electrostatic force of attraction
This requires more energy to overcome the ionic bonds in MgO than in NaCl
637
Why do metals and ionic compounds both have high melting points?
They both have many strong bonds in a giant structure
which requires a lot of energy to overcome
638
Fluorine atom gains an electron to become F1-.
Is fluorine oxidised or reduced?
reduced
OIL RIG
Reduction is gain of electrons
639
Name the complex ion and give its valency
OH
hydroxide ion
OH 1-
640
What is the difference between an ionic bond and a metallic bond?
both electrostatic attraction
both giant structure with many bonds
Both contain metal ions
BUT
Metallic is the attraction between a metal ions and delocalised electrons
Ionic is the attaction betwen a metal ion and a negative ion (or oppositely charge ions)
641
Why do ionic compounds conduct electricity when molten or in solution but not when it is in solid form?
When ionic compounds are molten or in solution the charge ions are free to move and carry charge
When ionic compounds are solid, the ions are not free to move and cannot carry charge.
642
What is the valency of a silver ion?
Ag 1+
643
Describe how electron shielding makes elements like fluorine more reactive than chlorine
Fluorine is a smaller atom
Fluroine has less electrons (less electron shielding) between the nucleus and outer electrons and so has less repulsion on the outer shell of electrons
The outer shell gains electrons more easily
Therefore fluorine is more reactive than chlorine
644
What is the valency of a carbonate ion
CO3^2-
645
What is the formula of sodium chloride?
NaCl
Na is in group 1 - has valency of 1+
Cl is in group 7 - has valency of 1-
646
Why do ionic compound have high melting points?
There are many strong ionic bonds in a giant lattice structure
requires a lot of energy to overcome
647
What are the two possible iron ions?
Fe 2+ and Fe 3+
648
Explain in terms of electrons what happens when Mg reacts with O to form MgO
Mg loses 2 electrons to form Mg2+
O gains two electrons from Mg to become O2-
Two electrons are transferred from Mg to O
649
What is the formula of magnesium nitride?
Mg3N2
Mg is in group 2 - has valency of 2+
N is in group 5 - has valency of 3-
Use cross and drop….
650
What is the valency of a nitrate ion?
NO3^1-
651
Explain what happens in terms of electrons when Na reacts with Cl to form NaCl
Na is from group 1 and loses one electron to become Na+
This electron is transferred to the chlorine atom which gains one electron to become Cl -
Na+ Cl-
652
What is the valency of a lead ion?
Pb 2+
653
Why are ionic compounds brittle?
The positive and negative ions are in layers and are arranged in an alternating pattern. This means that the positive ions are attracted to the negative ions and the whole compound is held together tightly.
If a set of layers are disrupted and slide in one direction, the positive ions are now postioned across from each other and they repel.
This breaks the layers apart - making the compound brittle
654
Draw the dot cross diagram for sodium chloride
Na loses one electron- now has a full outer shell
Cl gains one electron - now has a full outer shell
This is called the octet rule
remeber to use square brackets and to write in the charge of the ions
655
What is the formula of sodium oxide?
Na2O
Na is in group 1 - has valency of 1+
O is in group 6 - has valency of 2-
Use cross and drop….
656
What is the valency of a sulfate ion?
SO4^2-
657
Why are metal malleable but ionic compounds are not?
Metals layers can slide but the delocalised electrons which form the metallic bond are not disrupted and they remain between the layers as they slide.
This means the metallic bond is not disrupted and the metal is still held together
Ionic compound layers are held together by the electrostatic attraction of oppositely charge ions. If these alternating ion layers are shifted on atom along, then similarly charge ions are now aligned and they repel and push the layers apart.
658
All salts have which type of bonding?
ionic bonding
The electrostatic attraction between oppositely charge ions
659
Which compound is ionic?
CH4 H2O MgCl2 NH3 CO2
Ionic compounds are formed when an electron is transferred from one atom to another.
Ionic compound consist of a metal from the left hand side of the periodic table which really wants to give electrons and a non-metal from the right hand side of the periodic table which really wants to gain electrons
CH4 H2O MgCl2 NH3 CO2
MgCl2 is the ionic compound- formed of a metal and non-metal
660
Calcium loses two electrons to become Ca2+.
Is calcium oxidised or reduced?
oxidised
OIL RIG
Oxidation is loss of electrons
661
What is the valency of a hydrogen ion?
H 1+
662
Define an ionic bond
electrostatic attraction between oppositely charge ions
663
What is the valency of an ammonium ion?
NH4^1+
664
Name the complex ion and give its valency
NO3
nitrate ion
NO3^1-
665
This is the complex ion, SO4. State its name and its valency
sulfate ion
valency is SO4 2-
666
What is the state symbol for a solid?
(s)
667
What is the state symbol for a gas?
(g)
668
What is the state symbol for a liquid?
(l)
669
What is the state symbol for an soluble substance in water or aqueous?
(aq)
670
When is a substance aqueous?
When the substance is soluble in water and water is present in the reaction
671
Give the types of salt which are always soluble
All nitrate salts are soluble
All sodium, potassium (group 1) or ammonium salts are soluble
672
State the solubility rule for halides
All Halides are soluble except for lead and silver
673
State the solubility rule for sulfates
All sulfates are soluble except for lead and barium
674
Which of the following salts are soluble?
Na2CO3 BaSO4 Mg(NO3)2 PbCl2
Na2CO3 Mg(NO3)2 are soluble
BaSO4 PbCl2 are insoluble
All sodium salts are soluble
All nitrate salts are soluble
All sulfate salts are soluble except for Barium
All halide salts are soluble except for lead
675
State the solubility rules for oxides, hydroxides and carbonates
All oxide, hydroxides and carbonates are insoluble except for sodium, potassium or ammonium
676
Outline the method for chromatography
draw a pencil line at the bottom of the paper using a ruler
create dots of ink along the pencil line
curl the paper into a cylinder (with the pencil line at the bottom) and fasten with a paper clip at the top
add a small amount of water to a beaker
stand the cylinder with the pencil line at the bottom in the baker making sure the water level is below the pencil line
leave until the solvent front approaches the top of the paper- remove the chromatogram
mark the solvent front and leave to dry
677
What is the pencil line called on a chromatogram?
The base line
678
When carrying out chromatography, why must the water level be below the pencil line (base line)?
Otherwise the ink samples would dissolve into the water and would not travel up the paper. You want the water to move up the paper- taking the ink with it.
679
What is the formula for finding the Rf value of an pigment in chromatography?
Rf= distance pigment moved from base line / distance solvent moved from base line
Remember your Rf values will always be less than 1.
You are using a ruler so you must measure to a mm. It is best to record the distance in mm to avoid any mistakes.
680
When carrying out chromatography on a sample of inks, what does it mean if the ink does not move from the base line?
That particular ink is insoluble in that solvent
681
When Alex carried out chromatography, none of his ink samples moved from the base line. What could Alex do to get the ink to move from the base line so that he can compare the ink samples?
The ink samples are not soluble in that solvent. Alex should change the solvent.
682
Amelie noticed that one sample of ink did not separate into different spots as it travelled up the chromatography paper, but it stayed as one spot. What can Amelie conclude about that sample of ink?
That sample of ink is soluble in water but is a pure sample with only one pigment. It is not a mixture of two pigments.
683
Amelia noticed that one sample of ink separated into two different spots as it travelled up the chromatography paper, with one dot travelling further than the other. What can Amelia conclude about that sample of ink?
That sample of ink is soluble in water but is a mixture of two pigments. It is not pure, not one pigment.
Note: One pigment is more soluble than the other and travels further up the paper.
684
In chromatography, what is the relationship between solubility of a pigment and its Rf value?
The more soluble a pigment is the further it travels up the paper, the larger the Rf value.
note: an Rf value can never be larger than 1
685
What doe the symbol Rf stand for?
Retardation factor
686
In filtration, what is the name of the substance which is trapped in the filter paper?
The residue
687
In fitration, what is the name of the substance which passes through the filter paper?
The filtrate
688
Which method below would separate water from salt?
filtration
chromatography
simple distllation
fractional distillation
evaporation
simple distillation
The water would evaporate and then condense in the Leibig condenser, dripping out the end as the distillate
689
Which method below would separate salt from seawater?
filtration
chromatography
simple distllation
fractional distillation
evaporation
evaporation
when heated, the water evaporates leaving the salt crystal behind.
690
Which method below would separate alcohol from water?
filtration
chromatography
simple distllation
fractional distillation
evaporation
Fractional distillation
The fractionating column contains glass beads which gives the inside of the column a very large surface area. If the temperature near the condenser is kept at 78 degrees (the boiling point of alcohol) alcohol and some water will evaporate from the solution and travel up the column. The large surface area allows the water to condense on the glass beads and drips back into the flask. Only the alcohol enters the condenser and dripps out the end as a pure alcohol distillate
691
Which method below would separate an insoluble salt from water?
filtration
chromatography
simple distllation
fractional distillation
evaporation
filtration
The insoluble salt is solid and is caught in the filter paper as the residue.
Note: it is best to wash the insoluble salt with distilled water to make a pure sample
692
Which method below would separate an insoluble salt from water?
filtration
chromatography
simple distllation
fractional distillation
evaporation
filtration
The insoluble salt is solid and is caught in the filter paper as the residue.
Note: it is best to wash the insoluble salt with distilled water to make a pure sample
693
Which method below would separate an ink sample?
filtration
chromatography
simple distllation
fractional distillation
evaporation
Chromatography
The most soluble pigment will travel the furthest up the chromatography paper.
694
Which method below would separate soluble salt from water?
filtration
chromatography
simple distllation
fractional distillation
evaporation
Evaporation
The salt is soluble, so filtration will not work. You must heat the solution and evaporate the water, leaving the salt behind
695
Which piece of equipment is used to separate two immiscible liquids?
Separating funnel
The less dense liquid will sit on top of the more dense liquid. When the layers have time to fully separate, the tap is open at the bottom of the funnel and the more dense liquid pours out.
696
Define a solvent
A liquid which dissolves a solute
697
Define a solute
A solid which dissolves in a solvent
698
Define a solution
A solution is formed when a solute dissolves in a solvent
699
What equipment would you need to carry out evaporation of a salt solution?
evaporating basin
Bunsen burner
heat proof mat
gauze
700
What equipment would you need to filter sand from water?
filter funnel
filter paper
beaker
701
How would you obtain pure salt from rock salt?
grind rock salt in a pestle and mortar
add water and stir to dissolve salt
fold filter paper and place in filter funnel
place filter funnel in beaker
pour solution into filter paper in parts- make sure to keep level of solution below edge of filter paper.
collect filtrate in beaker
Set-up evaporating basin over Bunsen burner using a tripod and gauze.
Pour filtrate in evaporating basin
Heat solution on medium flame until half volume
Leave solution to crystallise
Filter out crystals
Leave crystals to dry in warm place
702
How is mass of solute which dissolves related to the volume of solvent?
As the volume of solvent doubles, the mass of solute which dissolves doubles. They are proportional?
703
In chromatography, if a pigment or ink is not soluble in a solvent what would you observe?
The pigment would not move from the base line. Rf value would be zero.
704
What is the valency of a lead ion?
Pb 2+
705
What are the two possible valencies of copper ions?
Cu 1+ and Cu 2+
706
What are the two possible valencies of iron ions?
Fe 2+ and Fe 3+
707
What is the valency of a silver ion?
Ag 1+
708
What is the valency of a zinc ion?
Zn 2+
709
What is the valency of a hydrogen ion?
H +
710
What is the valency of a hydroxide ion?
OH 1-
711
What is the valency of a carbonate ion?
CO3 2-
712
What is the valency of a nitrate ion?
NO3 -1
713
What is the valency of a sulfate ion?
SO4 2-
714
What is the valency of an ammonium ion?
NH4 +
715
I am a type of salt which is insoluble if I am bonded with a lead or barium metal? What type of salt am I?
sulfate salt
716
I am a type of salt which is insoluble if I am bonded with a lead or silver metal? What type of salt am I?
halide salt
717
I am measured in g per 100 cm3
What am I?
solubility
717
Define an element
A substance containing only one type of atom
718
Define a compound
A substance containing more than one different type of atom chemically bonded together
719
Write the chemical equation for the decomposition of H2O2
2H2O2 –> 2H2O + O2
720
What is a molecule?
When two or more atoms are chemically bonded together
721
What is the word equation for the decomposition of hydrogen peroxide
hydrogen peroxide –> water + oxygen
722
How can you prepare oxygen in the lab?
Add hydrogen peroxide (H2O2) to a conical flask.
Connect a bung with tubing to the top of the conical flask.
Fill a trough with water
Submerge two or three test tube in the water removing all the air from them
Arrange each of them upside down filled with water- ready to bubble oxygen into them
Remove the bung and add a small spatula of manganese dioxide (catalyst) and quickly replace the bung.
Allow a small amount of bubbles to escape before you start collecting the pure oxygen by down ward displacement.
723
What type of reaction is this?
2H2O2 –> 2H2O + O2
decomposition
A –> B + C
724
What would you observe during the decomposition of hydrogen peroxide using the catalyst manganese dioxide?
Fizzing
manganese dioxide is not used up
725
What is the name of the method used to collect oxygen druring the decomposition of hydrogen peroxide?
Downward displacement of water
726
What is the test for oxygen?
glowing splint
relights
727
How can you make carbon dioxide in a lab?
Add a sample of CuCO3 in a test tube.
Add a bung and delivery tube to the end of the test tube
Collect the carbon dioxide by upward displacement of air by placing the delivery tube into an upright test tube.
NOTE: CO2 is more dense than air and will fill the test tube- pushing the air out.
728
Write the word equation for the reaciton thermal decomposition of copper (II) carbonate
copper (II) carbonate –> copper oxide + carbon dioxide
729
What is the test for carbon dioxide?
bubble through limewater
limewater turns cloudy
730
What is the test for carbon dioxide?
bubble through limewater
limewater turns cloudy
731
Write the word equation for the combustion of meagnesium.
combustion means reaction with oxygen
magnesium + oxygen –> magnesium oxide
732
What is the chemical equation for the thermal decomposition of copper (II) carbonate?
CuCO3 –> CuO + CO2
733
What type of reaction is this?
2Ba + O2 –> 2BaO
reaction with oxygen so it is called combustion or oxidation
734
Why can’t we collect carbon dioxide by downward displacement of water?
Carbon dioxide is soluble in water- some of it will dissolve in the water
735
What would you observe when you burn magnesium in oxygen?
grey solid turns to a white powder
very bright light
736
How can we collect the gas carbon dioxide?
Upward displacement of air
CO2 is more dense than air and will fill an upright test tube- pushing (displacing) the air up and out.
737
Is this reaction endothermic or exothermic?
Magnsium + oxygen –> magnesium oxide
exothermic - both heat and light are given off
738
Write the word equation for the combustion of sulfur
sulphur + oxygen –> sulfur dioxide
739
What would you observe if you plunge a metal oxide into water with a few drops of universal indicator?
The indicator will turn blue as metal oxides are alkaline
740
Write the chemical equation for the combusiton of sulfur
S + O2 –> SO2
741
What would you observe if a non-metal oxide were added to water with a few drops of universal indicator?
It would turn red
non-metal oxide in water forms an acid
H+ ions are present
742
When sulfur burns in oxygen, what is the colour of the flame?
blue
743
What are the three oxides which form in a car engine?
sulfur in fuel form sulfur dioxide
nitrogen in air forms nitrous oxide
carbon in fuel form carbon dioxide
These all cause the rain to be acidic -acid rain
744
What is the most abundance substance in air after nitrogen and oxygen?
argon
745
List two gases which contribute to the greenhouse effect
carbon dioxide is a green house gas
so is methane!!
746
What is the percentage of nitrogen in air?
78%
747
What is the percentage of oxygen in air?
21%
748
When finding the percentage of oxygen in air copper turning are used. Why must the copper be in excess? (You have much more copper than needed for the reaction)
You are measuring the percentage of oxygen in air by reacting it with a metal. To get all the oxygen to react you need excess copper.
When heated in air copper will turn from orange/pink to black as copper oxide is formed
Eventually all the oxygen will be used up, allowing you to measure the remaining gases in air.
749
Below are the results from the percentage of oxygen in air experiment using copper turnings
Starting volume 100 cm3
End volume 79 cm3
Find the percentage of oxygen in air
(100 - 79) / 100 = 21%
750
What is the valency of the hydroxide ion?
OH^1-
751
Describe the set-up for measuring the percentage of oxygen in air with copper turnings.
Two syringes with glass tubing between.
Excess copper turnings placed in the middle of the tube.
Start with exactly 100 cm3 of air by reading the syringe volume at eye level.
Heat the glass tube under the copper turnings using a roaring flame.
Push the air from one syringe to another repeatedly until the volume no longer changes- all the oxygen has been used up.
Allow the gas to cool before reading the new volume of gas.
((Starting volume - final volume) /starting volume) x 100= percentage oxygen in air
752
What are the atoms in group 7 called?
Halogens
753
What is the colour change of the copper turnings in the percentage of oxygen in air experiment?
orange/pink to black
754
What is the valency of the sulfate ion?
SO4^2-
755
Why do we need the gas to cool before taking the final volume reading in the percentage of oxygen in air experiment?
gas expands when heated.
Fair test.
756
What is the valency of the ammonium ion?
NH4^+
757
Percentage of oxygen in air can be measured using the reaction of copper with oxygen or the reaction of iron wool and oxygen. What is the main difference with these two experiments?
Percentage of oxygen in air can be done more quickly using copper turnings. Copper is heated using a roaring flame.
Percentage of oxygen in air is much slower (1-2 weeks) when using iron wool. Rusting is a very slow reaction.
758
What are the elements in group 1 called?
Alkaline metals
759
What is the valency of the carbonate ion?
CO3^2-
760
What are the metals in group 2 called?
Alkaline Earth metals
761
Name the only two elements which are liquid at room temperature
bromine and mercury
762
What are the elements in group 0 called?
Noble gases
763
What is special about the transistion metals?
They form colourful compounds
They have more than one valency
Fe2+ Fe3+
764
Complete the reaction of iron with sulfur
iron + sulfur –>
iron + sulfur –> iron sulphide
765
Name the diatomic elements
Hydrogen
Nitrogen
Fluorine
Oxygen
Iodine
Chlorine
Bromine
766
Name the compound
NH4OH
ammonium hydroxide
767
Name the compound
Na2CO3
sodium carbonate
768
Name the compound
MgSO4
Magnesium sulfate
769
Name the compound
Ca(NO3)2
calcium nitrate
770
Name the compound
FeS
Iron sulfide
771
A metal oxide which can dissolve in water will turn universal indicator __________________ because it is _________________
A metal oxide which can dissolve in water will turn universal indicator blue because it is alkaline
772
What does accurate mean?
close to the true value
773
A non-metal oxide added to water will turn universal indicator ______________ because it is an ____________
A non-metal oxide added to water will turn universal indicator red because it is an acid
SO2 in water form H2SO4
774
What is an anamolous result?
A result which does not fit the pattern
775
What should you do with an anamolous result?
record it but cross it out and carry out another reading- do not include it in an average
776
How should you measure the volume of a liquid in a measuring cylinder accurately?
Place the measuring cylinder on a flat and level surface
Read the volume at eye level and the bottom of the meniscus
777
Describe what a precise instrument is
An intrument that gives readings with more decimal places or an instrument with smaller increments (resolution)
Some measuring cylinders read to +- 1 cm3
Some measuring cylinders read to +- 0.2 cm3
778
What would the colour change be for the rusting of iron in the percentage of oxygen experiment?
grey to red/brown
779
How do you know when reading are reliable?
When the readings are all very similar or clustered closely
780
Name gases which contribute to the greenhouse effect
carbon dioxide and methane
781
What is chemical bonding?
The joining, chemically of two or more atoms to form a compound.
782
What is an ion?
An ion is an electrically charged atom or group of atoms formed by the loss or gain of electrons.
783
Why would an atom loses or gain electrons in the outermost shell?
This loss or gain of electrons takes place to gain a full outer shell of electrons.
784
Ionisation of metals and non-metals:
Metals: all metals lose electrons to other atoms to become positively charged ions.
Non-metals: all non-metals gain electrons from other atoms to become negatively charged ions.
785
What holds the positive and negative charges of ionic compounds together?
The positive and negative charges are held together by the strong electrostatic forces of attraction between opposite charges.
786
What is an ionic bond?
An ionic bond is the electrostatic force of attraction between positive and negative ions.
787
What happens when an atom loses an electron?
When an atom loses an electron it forms positively charged ions called cations.
788
What happens when an atom gains electrons?
When an atoms gains electrons it forms negatively charged ions called anions.
789
What is a lattice structure?
A regular arrangement of alternating positive and negative ions.
790
How do you describe the forces of attraction between the positive and negative ions of a giant lattice structure?
The forces of attraction between the positive and negative ions of a giant lattice structure are very strong.
791
What are the 3 physical properties of ionic compounds?
Ionic compounds have high melting and boiling points.
Ionic compounds are soluble in water but insoluble in organic solvents.
Ionic compounds conduct electricity only when molten or when dissolved in water because the ions are mobile.
792
Why do Ionic compounds have a high melting and boiling point?
Because a lot of heat energy is required to break the strong force of attraction..
793
Why are ionic compounds soluble in water but not organic solvents?
They are soluble in water because the water molecules are able to separate the ions from one another and keep the ions in solution.
794
When are covalent compounds formed?
Covalent compounds are formed when electrons are shared between atoms.
795
What are the properties of covalent compounds?
Covalent compounds have low melting points and boiling points because the intermolecular attractive forces are weak.
Covalent compounds are insoluble in water but can dissolve in organic substances.
Covalent compounds do not conduct electricity because they have no free electrons or ions.
796
What are the allotropes of carbon?
Diamond and graphite are allotropes of carbon that have giant covalent structures.
797
What are the three properties of diamonds?
Diamond does not conduct electricity
Diamond has very high melting and boiling point.
Diamond is extremely hard and dense
798
What is diamond used in?
Diamond is used in jewellery and as cutting tools.
799
In a diamond, how is a giant tetrahedron covalent structure formed?
Each carbon atom bonds with four other carbons, forming a tetrahedron.
800
What are the three properties of graphite?
Graphite conducts electricity.
Graphite has a very high melting point.
Graphite is soft and slippery.
801
What are the covalent bonds of a diamond like?
All the covalent bonds in diamonds are identical and strong with no weak intermolecular forces.
802
Why does graphite conduct electricity?
The free electrons that exist in between the layers and are free to move and carry charge, hence graphite can conduct electricity.
803
In graphite, how is a giant hexagonal covalent structure formed?
Each carbon atom is bonded to three others forming layers of hexagonal-shaped forms, leaving one free electron per carbon atom.
804
Why is graphite slippery and smooth?
The covalent bonds within the layers are very strong but the layers are connected to each other by weak intermolecular forces, hence the layers can slide over each other making graphite slippery and smooth.
805
What is graphite used for?
Graphite is used in pencils, industrial lubricants and is also used to make carbon electrodes for electrolysis.
806
Why do diamond and silicon (IV) oxide not conduct electricity?
Diamond and silicon (IV) oxide do not conduct electricity because all its valence electrons are used in bonding - no free electrons.
807
In silicon (IV) oxide or silicon dioxide, how is a giant tetrahedron covalent structure formed?
A tetrahedron is formed because each silicon atom is bonded to four oxygen atoms but each oxygen atom is bonded to only two silicon atoms.
808
What does silicon (IV) oxide or silicon dioxide or SiO2 naturally occur as?
SiO2 is a macromolecular compound that occurs naturally as sand and quartz.
809
What are the 4 properties of silicon (IV) oxide?
Silicon (IV) oxide is very hard.
Silicon (IV) oxide has very high melting and boiling points.
Silicon (IV) oxide does not conduct electricity.
Silicon (IV) oxide has lots of very strong covalent bonds and no intermolecular forces.
810
What is metallic bonding?
The electrostatic force of attraction between positive metal ions and a sea of delocalized electrons.
811
Why are metallic bonds strong?
Metallic bonds are strong because of the attraction between the positive metal ions and the negatively charged delocalized electrons.
812
What are the 3 properties of metals?
Metals have high melting and boiling points.
Metals are good thermal and electric conductors.
Metals are malleable(can be hammered into shape) and ductile (can be drawn into a wire).
Metals are lustrous.
Metals are sonorous.
813
Why do metals have a high melting and boiling point?
There are many strong metallic bonds in giant metallic structures therefore a lot of heat energy is needed to overcome forces and break these bonds.
814
Why are metals good conductors of electricity?
Metals can conduct electricity because the sea of delocalized electrons is able to move.
815
Why are metals, good thermal conductors?
Conduction of heat is due to vibrations of the atoms passing on the energy from one atom to the next.
816
Why are metals malleable and ductile?
The regular arrangement of metal ions means that the layers of ions are able to slide over each other easily without the metal shattering, making metals malleable and ductile.
817
Practical studying:
Drawing Ionic Bonds.
Drawing Covalent Bonds.
Metallic Bonds.
818
Metal + non-metal bonding =
Metal + non-metal = ionic bond.
819
Non-metal + non-metal bonding =
Non-metal + non-metal = covalent.
820
Metal + metal bonding =
Metal + metal = metallic.
821
What is an alloy?
An alloy is a mixture of two or more elements , where at least one element is a metal
822
What are the four properties of non-metals?
Non-metals are dull.
Non-metals are poor conductors of electricity and heat.
Non-metals are brittle.
Non-metals have a low boiling and melting point.
