Matter And Materials Flashcards
(229 cards)
1
Q
What can materials be classified into
A
Pure substances and impure substance
2
Q
What can impure substances be classified into
A
Homogeneous mixtures and heterogenous mixtures
3
Q
What can pure substances be classified into
A
Elements and compounds
4
Q
What can elements be classifieds into
A
Metals and non metals
5
Q
Where are metals found on the periodic table
A
On the left side
6
Q
Where are non metals found on the periodic table
A
On the right side
7
Q
what are the metals in group one called
A
Alkali metals
8
Q
What are the metals in group 2 called
A
Alkali earth metals
9
Q
what are the group 17 element
A
Halogen
10
Q
What are the group 18 elements
A
Noble gasses
11
Q
What are some properties of non metals
A
They are dull, brittle, not sonorous, heat and electrical insulators
12
Q
What are some qualities of metals
A
Have lustre, are brittle, are ductile, are sonorous, are heat and electrical conductors
13
Q
What are electrical cables usually made out of
A
Copper because it is a good electrical conductor and is relatively inexpensive
14
Q
What are copper wires usually covered with
A
plastic because plastic is an insulator
15
Q
What are heater and stove elements made out of
A
Nichrome wire because it has high resistance and as a result heat is generated when a electrical current flows through it.
16
Q
What are cooking pots made out of
A
Metal because metal is a good conductor of heat. The handles of pots are made out of plastic or other non-metals because they are thermal insulators
17
Q
what are winter clothes made out of
A
Thick fabrics which trap air. Air is a thermal insulator, which helps maintain body temperature.
18
Q
What are magnetic metals called
A
Ferromagnetic
19
Q
What are the three magnetic metals
A
Iron, cobalt and nickel
20
Q
What are magnets used fo in real life
A
Electric motors, speakers and compasses
21
Q
What are semi metals or metalloids
A
They are elements that have properties of both metals and non metals
22
Q
What are the 8 metalloids
A
Boron, silicon, germanium, arsenic , antimony, tellurium, polonium and astatine
23
Q
Do most metalloids behave like metals or non metals
A
Non metals
24
Q
How do metalloids act like non metals
A
They are brittle
25
How do metalloids act like metals
They are good conductors of electricity, but not as good as metals
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What is an interesting property of metalloids
They conduct electricity better at higher temperature
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What are metalloids used in
In microchips
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What metalloids are used in microchips
Silicon and germanium.
29
When is a compound formed
When two or more elements combine chemically in a fixed ratio
30
What is a mixture
A combination of two or more substances in which each substance retains their individual properties
31
What are the two types of mixture
Homogenous and heterogenous
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What is a homogenous mixture
A mixture in which the composition is the same throughout and consists of two or more substances in the same phase
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What is axis a mixture of and what type of mixture is it
Nitrogen, oxygen and small amounts of carbon dioxide. It is a homogenous mixture
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What is saline
A homogeneous mixture of water and solid salt
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What is a metal alloy
A homogenous mixture of one solid dissolved in another solid
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What is an sample of a metal alloy
White gold
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What is white gold a mixture of
Gold, palladium, nickel and traces of other metals
38
What is a heterogenous mixture
A mixture in which the composition is not uniform. You can see the different substances. Any combination of substances that do not dissolve in one another is a heterogenous mixture
39
What will happen when sand is mixed with water
It will form a suspension. Sand particles do not dissolve in water if left to stand the sand will sink to the bottom
40
What is it called when two liquids do not mix
They are said to be immiscible
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what is an example of an immiscible mixture
Oil and water
42
What is an example of emulsion
When a mixture of oil and water is shaken and the oil separates into tidy droplets which disperse throughout the water
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What can be added to emulsions to prevent them from separating
Emulsifiers
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What is mayonnaise
An emulsion of egg yolk and oil
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How can mixtures be separated
By physical means
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How can a salt water solution be separated by physical means
Through evaporation and condensation
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How can oil and water be separated
By using a separating funnel
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How can iron filings and sand be separated by physical means
By a magnet
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How can water and sand by separated by physical means
Filtration
50
How can the purity of a substance be checked
By using boiling and melting points
51
How can purity be checked by using boiling and melting points. Eg. Alcohol and water
Looks like a pure mixture, but can test if it is by seeing if it boils at 100˚c or less. If it is less, the substance is not pure water.
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What is another way of checking purity
A process called chromatography
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What is chromatography
It is when the substance being tested is dissolved in a liquid such as water. The solution is then passed through another material, such as paper. If the substance is not pure, the different parts travel through the paper at different speeds and are separated
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Who was Robert brown
A botanist studying pollen grains suspended in water under a microscope.
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What did Robert Brown discover
That minute particles ejected by the pollen were moving around in a random jittery motion.
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What is this random motion of the small particles ejected by the pollen grains called
Brownian motion
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How did scientists explain this motion
They explained this motion by assuming that all matter is made out of tiny particle, which they called atoms, which are constantly moving
58
What happens when ink is dropped in water
The ink slowly diffuses into the water, this is done by the movement of the water particles
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What determines properties of material
The way the atoms are bonded to one another
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What properties does the bonding of atoms determine
Whether a substance is solid, liquid or gas at room temperature
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What are the properties of a solid
The particles vibrate in place, strong forces hold the atoms together in a crystal lattice, has its own shape and volume and the particles are close together and not compressible
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What are the properties of a liquid
Forces still hold particles together but are weaker than the forces between particles in a solid. particles are able to change place and are therefore able to move over one another and can be poured. It takes on the shape of its container, but has its own volume and the particles are close together and not compressible
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What are the properties of a gas
Forces between particle are almost non-existent. Particles are free to move and thus fill the whole container. Has no shape, fills container, fills container, has volume of container. Particles are far apart and are compressible.
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What does it mean if all particles are moving but boot at the same speed.
It means that some particles have higher kinetic energy and some have lower kinetic energy
65
What is temperature
It is proportional to the average kinetic energy of an objects particles
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What happens when the temperature of a substance changes
Substances may change phase
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What is the melting point
The point at which a solid changes to a liquid
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What is the freezing point
The point at which a liquid becomes a solid
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What is the boiling point
The point at which a liquid becomes a gas or a gas becomes a liquid
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What is evaporation
Not all particles have the same kinetic energy and there are strong forces between the particles. The particles at the top may have more kinetic energy and are able to overcome the force of attraction and escape from the liquid forming a vapour
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What happens to the remaining particles once the top layer of the liquid has evaporated
They have less kinetic energy cause the temperature of the remaining liquid to drop. This is used to regulate body temperature
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How is evaporation used to regulate body temperature
When we are hot, we sweat, when the sweat evaporates, it cools our body’s down.
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What are the similarities between evaporation and boiling
They both result in a phase change from liquid to a vapour
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What are the differences between evaporation and boiling
1. evaporation takes place at any temperature, boiling takes place at specific temperature.
2. Evaporation takes place at the surface only, boiling occurs throughout the liquid
3. Boiling takes place when the pressure of the vapour in the bubbles is equal to the atmospheric pressure
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What is the relationship between forces and boiling point
The stronger the forces between the particles in a substance are, the higher the boiling point. The weaker the forces between the particles in a substance are, the lower the boiling point. This is because the stronger the forces, the more energy is required to break the bonds between the particles.
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What happens when a liquid is boiling
There are bubbles of vapour that form during this process that rise to the top and release their vapour.
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How does atmospheric pressure affect boiling point
The boiling point is determined by the atmospheric pressure because a substance will only boil when the pressure in the bubbles in the liquid are the same as the atmospheric pressure. They are directly proportional, the higher the atmospheric pressure, the higher the temperature needs to be for a substance to boil.
78
What is sublimation
When a substance changes directly from a solid to a gas
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What is an example of sublimation
When Iodine crystals are heated, they do not become a liquid by immediately form iodine gas
80
What happens when a solid is heated
The particle start to vibrate more, thus increasing their kinetic energy, and the bonds between them start to break. The particles also have forces of attraction, and if very close together, they also have forces of repulsion. So in addition to increased kinetic energy, they also have increased potential energy
81
What happens when a solid is heated to its melting point
The heat does not increase their kinetic energy, but their potential energy. At this temperature the rigid structure of the crystal lattice starts to break apart into the liquid phase only once al the molecules have broken free can they start to gain kinetic energy and the liquid’s temperature starts to rise
82
What happens when a liquid is heated to its boiling point
The temperature remains constant until all the liquids have been changed into vapours. the heat is converted into potential energy
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Why is boiling a substance often more difficult that melting a substance
Because during the boiling, the bonds of the substance have to actually break, whereas when it is melting, they just gain more kinetic and potential energy
84
What is the current model of the atom
There is a nucleus in the centre of an atom, it consists of protons and neutrons. Electrons orbit around the nucleus
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What is the atomic number
The number of protons in an atom. It determines what element it is going to be.
86
What is the atomic mass of an atom
This is the nucleus because the nucleus is the mass of the atom thus the atomic mass is the protons plus the neutrons
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What is an isotope
Atoms of the same element which have different mass numbers. They have the same number of protons, but different number of neutrons
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What are the isotopes of chlorine
Chlorine 35 and chlorine 37
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What is a cation
A positively charged ion
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What is an anion
A negatively charged ion
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What is an ion
A charged atom
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When is an atom positive
When it has lost electrons
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When is an atom negative
When it has gained electrons
94
What do the names of negative ions usually end with
-ide
95
What two assumptions did Bohr make
1. That electrons can only move in fixed, permitted orbits
2. That the electron moving that fixed orbit had a definite energy which could not change while the electron was moving in the specific orbit
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What are the fixed energies that electrons in an atom can have called
Energy levels
97
what can an electron not do while travelling in an energy level
They can not emit energy or absorb energy
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How can electrons radiate energy
The electron has to fall from a high energy level to a lower one
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How do electrons absorb energy
It has to jump to higher energy levels
100
What is quantised energy
The energy radiated or absorbed by electrons. It is limited to certain energy values determined by the energy differences between the energy levels
101
What does the atomic model take into consideration
The wave nature of electrons, which is provided by the fact that streams of electrons produce diffraction patterns
102
What is it possible to calculate in an atom
The energy, the shape and most likely the position of an electron wave
103
What are orbitals
The regions where electron waves are most likely to be found.
104
What are the two orbitals
S-orbital
| P-orbital
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What is the s-orbital
It is spherical and they are arranged symmetrically around the nucleus, but differ in size.
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How many a-orbitals are there in every energy level
Only one
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A maximum of how many electrons can be found in the s-orbital
2
108
The maximum number of electrons that the p-orbital can hold is
6, two in each part of the p-orbital
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What is the p-orbital
It is shaped like an infinity sign and comes in groups of 3. They are found in the second energy level onwards. They can hold a total of 6 electrons
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What are valance electrons
Electrons found on in the putter most energy level. It is he same as the group numbers
111
What are the core electrons
They are the electrons found in the inner most energy level
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What is the s-block
Groups one and two, this means that the elements found in these groups have their outermost electrons in an s-orbital
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What is the p-block
Groups 13 to 18 this means that the elements found in these groups will have their valance electrons in a p-orbital
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Groups
Vertical columns
Elements in a group have similar chemical properties
Group numbers enables the charge of an ion to be found
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Periods
Horizontal rows
One atom differs from the neighbouring atom by one proton
Period number is = to the number of the outermost energy level
116
Metals
Are found on the left side
Generally have few valance electrons
Generally lose electrons easily, so they for a positive ion
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Non-metals
Right side
Late number of valance electrons
Accept additional electrons, so they form negative ions
118
Noble gasses
In group 18. They are extremely stable because their outermost energy level is completely full, so they do not bond with other substances
119
What determines the reactivity of a substance
The presence of unpaired electrons
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What happens to atoms during a chemical reaction
They often gain or lose atoms to gain noble gas status.
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What are the gradually changing properties of the elements in a given period on a periodic table associate with
With gradually changing valance electron configuration
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What is the atomic radius
It is the radius of an atom, from the nucleus to the outermost electrons.
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How does the atomic radius change on the periodic table
It decreases from left to right and increases from top to bottom
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Why does the atomic radius decrease from left to right
Because the forces of attraction between the nucleus and the electrons increases, cause long the atom to become more compressed
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Why does atomic radius increase from top to bottom
Extra energy levels
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What is atomic density
The mass per unit volume. This means that it is the size of the atom as well as the in which they are packed together.
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Which atoms are more dense
Non-metals because their atoms are not packs as tightly together.
128
In metals, how does density increase/decrease on the periodic table
From left to right increases
| Top to bottom increases
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Why does density increase from left to right
Atomic radius decreases and atomic mass increases
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Why does density increase from top to bottom
Atomic radius increases, atomic mass increases
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What is ionisation energy
The energy required to remove an electron from a single atom in the gaseous phase
132
How does ionisation energy increase/decrease on the periodic table
It increases from left to right
| It decreases from top to bottom
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What is electron affinity
The energy liberated when an electron is added to an atom in the gaseous phase
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How does electron affinity increase/decrease on the periodic table
It increases from left to right
| It decreases from top to bottom
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What is electronegativity
It is an indictaion of the attractive force which an atom exerts on a shared electron pair
136
What is the most electronegative element
Florine
137
How does electronegativity increase /decrease on the periodic table
The same wa as electron affinity
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What are the properties of the alkali metals
Most reactive because they have only one valance electron. Not found in their elementary form in nature, but in compounds. Once the elements have been extracted, they have to be stored in an inert liquid so that they do not react. They all react with cold water to produce hydrogen and a hydroxide. They are all soft and light gray.
139
What are the properties of the alkali earth metals
They are also very reactive because they only have 2 valance electrons. They all react with cold water, except for beryllium, to produce hydrogen and a hydroxide. All, apart from beryllium, are light grey, relatively soft and are good conductors of heat and electricity
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What’s re the properties of the halogens
They are very reactive because they have 7 valance electrons. All have relatively low melting points. At room temperature, Florine and chlorine are gases, bromine is a liquid and iodine and astatine are solids
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What are the properties of the noble gases
They are exceptionally unreactive. They are gases at room temperature
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What is the bond between two metals called
A metallic bond
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What is the bond between two nonmetals called
A covalent bond
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What is the bond between a metal and a nonmetal called
An ionic bond
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Ionic bond
A transfer of electrons
One is an electron accepter(forms a negative ion) and one is an electron donor (forms a positive ion)
Ions pack in an ionic crystal lattice
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What are two important exceptions on the periodic table
Pb and Sn are in group IV but act like tradition metals (2+)
Ag is a transition metal but always has a charge of 1+
Although the transition metals usually have a charge of 2+, many have more that one charge
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What are the complex ions with a single charge
```
NH4^+
H3O^+
OH^-
NO3^-
NO2^-
ClO3^-
MnO4^-
HCO3^-
```
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What are the complex ions with a couple charge
```
CO3^2-
SO4^2-
SO3^2-
CrO4^2-
Cr2O7^2-
```
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What are the complex ions with a triple charge
PO4^3-
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Ammonium
NH4^+
151
What is hydroxide
OH^-
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What is nitrate
NO3^-
153
What is nitrite
NO2^-
154
What is chlorite
ClO3^-
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What is permanganate
MnO4^-
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What is hydrogen carbonate
HCO3^-
157
What is carbonate
CO^2-
158
What is sulphate
SO4^2-
159
What is sulphite
SO3^2-
160
What is chromate
CrO4^2-
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What is dichromate
Cr2O7^2-
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What is phosphate
PO4^3-
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what does the ending -are represent
A radical containing an oxygen
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What does the ending -ite represent
A radical containing one less oxygen than the corresponding -ate radical.
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Covalent bonding
Sharing of electrons.
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What is a group of covalently bonded atoms
A molecule
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What is a molecule
A group of covalently bonded atoms
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What is a bonding pair
A shared electron pair
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What are lone pair
Pairs of electrons that do not bond
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What is a double bond
When there are two bonding pairs
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1
Mono
172
2
Di
173
3
Tri
174
4
Tetra
175
5
Penta
176
Metallic bonding
Metal atoms loose their valance very easily leaving empty orbitals. Freed electrons able to move sassily from one metal ion to another by the force of attraction between positive ions and the “sea” of negative electrons.
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What is the relative formula mass
The relative mass of ionic substances
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What is the relative molecular mass
The relative mass of covalent substances
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How do you calculate relative mass
Add up the relative atomic masses of each o the elements
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What happens to the positive and negative ions that form when electrons are transferred from metal atoms to non-metal atoms
They are attracted to one another and form an ionic crystal lattice
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What is the best known example of an ionic crystal lattice
Sodium chloride ( table salt )
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What are the properties of ionic compounds
* They are solids at room temperature and have high melting points
* Solid ionic compounds do not conduct electricity but liquid ones can. Most ionic compounds dissolve in water forming and electrolyte solution that will conduct electricity
* they are hard and brittle
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Why did ionic compounds have high melting points and whey are they solid at room temperature
Because the forces holding the positive and negative ions together in the crystal lattice are very strong. It thus take a lot of energy to pull ions apart.
184
Why can solid ionic compounds not conduct electricity
Because the charged particles (ions) are not free to move.
185
Why can liquid ionic compounds conduct electricity
Because once it is melted, the ions are free to move around and they act as a charge carrier
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Why do ionic compounds dissolved in water conduct electricity
Because they dissolve, the ions are free to move
187
Why are ionic substances hard and brittle
Because when pressure is put on an ionic compound, the layers of ions move and like charged ions line up. The repulsion causes the crystal to break.
188
What are intramolecular bonds
The covalent bonds holding the atoms in a molecule together. They are strong
189
When is water a polar molecule
Because the nucleus of the oxygen atom has more protons than hydrogen’s nucleus
190
What are intermolecular forces
They are the forces holding the molecules together. They are weak forces between a slightly positive side and a slightly negative side of a molecule.
191
Explain how easy it would be to break he intermolecular and the intramolecular forces in water apart
The intermolecular forces would be easily broken, but the intramolecular forces would be very difficult to break apart.
192
What do the intermolecular forces between water molecules in the sold phase result it
A tetrahedral arrangement
193
Why does ice occupy a greater volume than water
Because of the tetrahedral arrangement. Thus the density of ice is less than the density of water.
194
Why is ice being less fence than water not normal
Because usually, the solid form of a substance is more fence than it’s liquid form
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Why is it crucial to the environment that ice is less dense than water
Because in cold parts of the world, when water freezes, it acts as an insulator to the water below, keeping the aquatic life safe.
196
What would happen if ice behaved like normal compounds
In cold weather, the top layer of water would freeze and sink to the bottom, this would continue to happen until the whole lake was frozen. When warmer weather came, the top layer of ice would melt, and the water would act as an insulator to the ice below
197
What are the properties of covalent molecular structures
* They have low melting points and are gasses at room temperature
* They do not conduct electricity
* Solid molecular substances are soft
198
Why do covalent molecular substances have low melting points
Because the intermolecular forces holding the molecules together are weak
199
What are examples of solid covalent molecular substances that are soft
Iodine crystals and bees wax
200
What are covalent network structures
They are substances consisting of non-metal atoms covalently bonded to non-metal atoms forming giant molecules
201
Why are covalent molecular substances so hard to break
Because they have very strong covalent bonds, and thus they have extremely high melting points
202
What element bonds covalently to form giant molecules
Carbon
203
What are allotropes
Different crystalline forms of the same element
204
What are the two allotropes of carbon
Diamond and graphite
205
How are the carbon atoms in diamond bonded
Each carbon style is covalently bonded to four other carbon atoms forming a giant molecule
206
What is the meting point of diamond and why is it so high
It is about 3500˚C because the bonds between all the carbon atoms are extremely strong
207
How are carbon atoms in graphite bonded
They are bonded to each other in layers. Each carbon atom is bonded to 3 other carbon atoms
208
What are the bonds between the layers of graphite like, and what does this result in
The bonds are weak so the layers can slide over one another. This is why graphite is slippery and can be used as a lubricant.
209
Why can graphite conduct electricity
Because it has 4 valance electrons, but only 3 are bonded, so the 4th is free to move around
210
What are the properties of covalent network substances
* Extremely high melting points and are solid at room temperature
* Hard (except graphite)
* Do not conduct electricity (except graphite)
211
What are the delocalised electrons in metals ions able to do
Move easily from one metal ion to another in the lattice. This forms a lattice of regularly spaced positive ions.
212
How is the metalic lattice held together
Through the force of attraction between the positive ions and the ‘sea’ of electrons
213
What are the properties of metallic substances
They conduct heat and electricity
They are malleable and ductile
Have a high density
Have metallic lustre
214
Why can metal substances conduct heat and electricity
Because the delocalised electrons are free to move
215
Why are metallic substance malleable and ductile
Because the metal ions and delocalised electrons continues to hold the metal together even under tender conditions
216
What does it mean that metallic substances have high density
The atoms are packed close to one another
217
How do metallic substances have metallic lustre
The loosely bound electrons reflect all frequencies of light, this causes the metal to shine
218
What are the particles in the crystal lattice of a covalent network
Atoms
219
What are the particles in the crystal lattice of a covalent molecular
Molecules
220
What are the particles in the crystal lattice of an ionic substance
Positive and negative ions
221
What are the particles in the crystal lattice of a metallic substance
Positive metal ions
222
What are the binding forces between particles in a covalent network substance
Covalent bonding
223
What are the binding forces between particles in a covalent molecular substance
Weak intermolecular forces
224
What are the binding forces between particles in an ionic substance
Electrostatic forces between positive and negative ions
225
What are the binding forces between particles in a metallic substance
Forces between ions and delocalised electrons
226
What is an example of a covalent network substance
Diamond
227
What is an example of a covalent molecular substance
Dry ice
228
What is an example of an ionic substance
Sodium chloride
229
What is an example of a metallic substance
Sodium silver
