Chemistry Paper 1 Flashcards
(154 cards)
1
Q
What is an atom?
A
The smallest part of an element that can exist
2
Q
What is an element?
A
A substance made of only one type of atom
3
Q
What is a compound?
A
A substance made of two or more different atoms chemically bonded together
4
Q
How are compounds formed?
A
From chemical reactions
5
Q
What is involved in a chemical reaction?
A
The formation of one or more new substances and an energy change
6
Q
What is a molecule?
A
A substance made of more than one atom chemically bonded together
7
Q
What is a mixture?
A
A substance made of more than one thing not chemically bonded together
8
Q
How can mixtures be separated?
A
Physical processes (filtration, crystallisation, simple distillation, fractional distillation and chromatography)
9
Q
Name three subatomic particles
A
Protons, neutrons, electrons
10
Q
State the relative masses and charges of the subatomic particles
A
Mass: Protons: 1, neutrons: 1, electrons: 0.
Charge: Protons: +1, neutrons: 0, electrons: -1
11
Q
What is the plum pudding model of the atom?
A
A ball of positively charge with negative electrons stubbed into it
12
Q
What did the gold foil experiment (alpha particle scattering) prove?
A
The atoms have a dense nucleus with a positive charge
13
Q
What did Chadwich discover?
A
The neutron
14
Q
What did Bohr’s experiments show?
A
That electrons are in specific shells
15
Q
What is the atomic number of an atom?
A
The number of protons in an atom
16
Q
What is the mass number of an atom?
A
The number of protons + the number of neutrons in an atom
17
Q
In the electron shell model, how are the subatomic particles arranged in an atom?
A
Protons and neutrons in the nucleus, electron orbiting in shells
18
Q
Why is the number of electrons in an atom equal to the number of protons?
A
As their charges cancel out
19
Q
How many electrons can go in the first shell?
A
2
20
Q
How many electrons can go in the second and third shell?
A
8
21
Q
What are the groups in the periodic table?
A
The columns, numbered 1, 2, 3, 4, 5, 6, 7, 0
22
Q
What can the group tell you about the electrons in an atom?
A
How many electrons in the outer shell. E.g. carbon is in group 4 so has 4 electrons in the outer shell
23
Q
What are the periods in the periodic table?
A
The rows in the periodic table
24
Q
What can the period tell you about the electrons in an atom?
A
How many shells an atom has. E.g. carbon is in the second period so has two shells
25
Why do atoms have no overall charge?
The number of electrons and protons are equal
26
Approximately how large are atoms?
Radius is about 0.1nm
27
How large is the nucleus compared to the whole atom?
About 1/10,000 the size
28
What are isotopes?
Atoms of the same element with a different number of neutrons
29
What is abundance?
The % of atoms in a sample with a particular mass
30
What is the relative atomic mass of an element?
An average value for the mass that takes account of the abundance of the isotopes of the element
31
In the modern periodic table, how are the atoms arranged?
By their atomic number and in groups according to chemical properties
32
Why do elements in the same group have similar chemical properties?
Because they have the same number of electrons in their outer shell
33
Before the discovery of protons, neutrons and electrons, how did scientists organise elements?
By their atomic weight
34
Why did Mendeleev leave gaps in his periodic table?
For elements that had not yet been discovered
35
Which discovery meant that organising elements by their atomic weight was not always correct?
Isotopes
36
Where are metals on the periodic table found?
To the left and bottom of the periodic table
37
What is an ion?
An atom which has lost or gained electrons
38
What kinds of ions do metals and non-metals form?
Metals form positive, non-metals form negative
39
What name is given to the group 0 elements?
Noble gases
40
Why are the group 0 elements unreactive?
They have full outer shells so do not need to lose or gain electrons
41
How does the boiling point of group 0 elements change down the group?
Increases down the group
42
Explain why the group 1 elements are called alkali metals?
They are metals that form alkalis when they react with water
43
What are the products of the alkali metals in a reaction with oxygen, water, halogen?
Oxygen: metal oxide
Water: metal hydroxide + hydrogen
Halogen: metal halide
44
Explain why the group 1 elements get more reactive down the group
More electrons, more shielding, weaker electrostatic attraction from the nucleus to the outer shell, easier to lose an electron
45
What is the name given to elements in group 7?
Halogens
46
How does the boiling point of group 7 elements change down the group?
Increases down the group
47
Explain why the group 7 elements get less reactive down the group
More electrons, more shielding, weaker electrostatic attraction from the nucleus to the outer shell, harder to gain an electron
48
What is a displacement reaction?
Where a more reactive element displaces a less reactive one from a compound
49
What are the three types of bond?
Covalent, ionic and metallic
50
What happens to the electrons in an ionic bond?
They are transferred
51
If an atom has gained electrons, what charge will it have as an ion?
Negative
52
If an atom has lost electrons, what charge will it have has an ion?
Positive
53
What type of elements will form ionic bonds?
Metal + non-metal
54
What is the charge on elements from group one and two?
Group 1: 1+, group 2: 2+
55
What is the charge on elements from group six and seven?
Group 6: 2-, group 7:1-
56
Describe the structure and bonding in an ionic compound
Giant ionic lattice held together by strong electrostatic force of attraction between positive and negative ions
57
State the melting and boiling points of ionic compounds
High
58
Explain the melting and boiling points of ionic compounds
High due to strong electrostatic forces of attraction which require a lot of energy to break
59
Explain why ionic compounds do not conduct electricity when solid
The ions are not free to move and carry charge
60
Explain why ionic compounds conduct electricity when molten or in solution
The ions are free to move and carry charge
61
What happens to the electrons in a covalent bond?
They are shared
62
What type of elements will form covalent bonds?
Non-metal + non-metal
63
What two types of substance have covalent bonds?
Giant covalent substances and small molecules
64
How many bonds does each carbon have in diamond?
4
65
Explain why diamond and silicon dioxide have high melting points
Giant structures, strong covalent bonds between the atoms, requires a lot of energy to break
66
Explain why most covalent substances do not conduct electricity
There are no electrons or ions that are free to move and carry charge
67
Making full reference to structure and bonding in graphite, explain how it conducts electricity
Each carbon has 3 bonds, 1 electron is delocalised and therefore free to carry charge through the graphite
68
Explain why graphite can act as a lubricant
Weak forces between layers which are free to slide over each other
69
What type of substance are methane and water?
Small molecules
70
Describe the structure of small molecules
Strong covalent bonds between atoms, weak intermolecular forces holding the molecules together
71
Explain why small molecules have low melting points
It is a simple molecular substance with weak forces between the molecules (which are easy to break)
72
What is a polymer?
Millions of small molecules joined together in a chain to form a large molecule
73
Why do larger molecules have higher melting points than smaller ones?
Intermolecular force strengthens with increased molecule size
74
What is graphene?
One layer of graphite
75
What is graphene used for?
Electronics and composite materials
76
What is fullerene?
Substance made of carbon atoms arranged in a cage
77
What are nanotubes?
Cylindrical fullerenes
78
What are nanotubes used for?
Electronics, nanotechnology and materials
79
What is the conservation of mass?
That atoms cannot be created or destroyed
80
When a metal forms a metal oxide, why does the mass increase?
Because oxygen atoms have been added
81
When an acid reacts with a metal, why does the mass decrease?
Because a gas is produced and escapes
82
What is relative formula mass?
The sum of the relative masses of each atom in a compound
83
What are the four state symbols and what do they stand for?
(s) solid (l) liquid (g) gas (aq) aqueous
84
What symbol do we use for relative formula mass?
Mr
85
(HT) What is a mole?
A number of particles
86
(HT) What is Avogadro's number?
6.022x1023
87
(HT) What formula relates moles, mass and Mr?
Mass = Mr x Moles
88
(HT) What is a limiting reactant?
A reactant that does not have enough mass to react with all the product
89
What is the unit for concentration?
g/dm3
90
Which formula relates concentration, mass and volume?
concentration = mass/volume
91
What is the reactivity series?
A list of elements ordered by their reactivity
92
How can metals be placed in order of their reactivity?
Add the metals to water or acid and see which ones react the most vigorously
93
What is the name for a reaction where oxygen is removed from a compound?
Reduction
94
Why is gold found in the Earth's crust as the metal itself?
It is unreactive
95
What process is used to extract metals less reactive than carbon?
Reduction with carbon
96
What process is used to extract metals more reactive than carbon?
Electrolysis
97
What is an ore?
A material containing enough metal in it for it to be economically worthwhile to extract the metal.
98
What is a displacement reaction?
A reaction in which a more reactive element takes the place of a less reactive element in one of its compounds or in solution
99
Define oxidation in the context of loss and gain of electrons
Oxidation is the loss of electrons
100
Define reduction in the context of loss and gain of electrons
Reduction is the gain of electrons
101
Define acid in terms of pH
A substance with a pH of less than 7
102
Define acids in terms of ions
A substance which releases H+ ions in solution
103
State the three common acids and give their formulae
Hydrochloric acid, HCl(aq), Sulphuric acid, H2SO4 (aq), Nitric acid, HNO3;
104
Which ions do the common acids form in solution?
HCI forms H+ and CI-, H2SO4 forms 2H+ and SO42-, HNO3, forms H+ and NO3-
105
What is a neutral solution?
A solution with a pH of 7. Water is an example
106
How do you measure pH?
With an indicator or pH probe
107
What is a base?
A metal oxide, hydroxide or carbonate that will react with an acid. E.g. copper oxide
108
What is an alkali?
A soluble base. E.g. sodium hydroxide
109
Which ions are always present in a solution of an alkali?
OH-
110
What is a salt?
A compound formed when some or all of the hydrogen from an acid is replaced by a metal
111
What type of salts are formed by the three main acids?
Hydrochloric acid produces chlorides, sulphuric acid = sulphates, nitric acid = nitrates
112
What is a neutralisation reaction?
A reaction involving an acid that results in a neutral solution
113
Which ions always react together in a neutralization reactions between acids and alkalis?
H+ and OH-
114
Write the equation showing the reaction between H+ and OH- ions
Н+ + OH- -> H2O
115
Complete the equation:
metal + acid
-> salt + hydrogen gas
116
Complete the equation:
metal hydroxide + acid
-> salt + water
117
Complete the equation:
metal oxide + acid
-> salt + water
118
Complete the equation:
metal carbonate + acid
-> salt + water + carbon dioxide
119
How do you make a soluble salt from an acid?
React the acid with a base. E.g. to make copper sulphate react copper oxide with sulphuric acid
120
If a salt is in solution, how do you extract it as a solid?
Allow the water to evaporate and it will leave the salt behind as a solid (crystallisation)
121
What is a strong acid?
An acid which completely splits up into its ions in water. E.g. when HCl is in water all the HCI molecules split up into H* and CI-
122
What is a weak acid?
An acid which will have some molecules which do not split up into their ions.
E.g. in ethanoic acid only some of the molecules will have split up into the ethanoate ion and H* ions.
123
What is the relationship between the strength of an acid and its pH?
As an acid increases in strength the pH decreases.
124
What is a concentrated acid?
An acid where there are lots of acid particles in the water.
125
What is a dilute acid?
An acid where there are fewer acid particles in the water.
126
How does pH depend on the concentration of H+ in a solution?
As the concentration of H* increases by a factor of ten, the pH decreases by one
127
What is electrolysis?
Using electricity to produce elements from an ionic compound
128
What is an electrolyte?
A liquid or aqueous ionic compound
129
What is the name for the positive electrode?
The anode
130
What is the name for the negative electrode?
The cathode
131
Do positive ions move to the anode or the cathode?
Cathode
132
Do negative ions move to the anode or the cathode?
Anode
133
What are the two main disadvantages of using electrolysis to extract metals?
Requires a large amount of energy to melt the compounds and to produce the necessary electricity
134
Why is aluminium oxide mixed with cryolite when extracting aluminium?
To lower the melting point
135
What is produced at the anode and cathode in the electrolysis of aluminium oxide?
Aluminium at the cathode and oxygen at the anode
136
Why does the anode need to be replaced in the electrolysis of aluminium oxide?
The oxygen reacts with the carbon electrode to produce carbon dioxide.
137
For a simple ionic liquid, where is the metal produced?
Cathode
138
For a simple ionic liquid, where is the non-metal produced?
Anode
139
In the electrolysis of an ionic solution, when will hydrogen be produced?
If it is more reactive than hydrogen
140
In the electrolysis of an ionic solution, when will oxygen be produced?
If the non-metal is not a halogen
141
What can happen to water molecules in the electrolysis of solutions?
They break down into hydrogen and hydroxide ions
142
What is a half equation?
An equation which shows electron transfer at one of the electrodes
143
State the law of conservation of energy.
Energy cannot be created or destroyed, it can only transferred from one place to another.
144
What is an exothermic reaction?
A reaction where energy is transferred to the surroundings.
145
Give two examples of exothermic reactions.
Combustion, respiration
146
What happens to the temperature of the surroundings during an exothermic reaction?
Increases
147
What is an endothermic reaction?
A reaction where energy is transferred from the surroundings.
148
Give two examples of endothermic reactions.
Thermal decomposition reactions, citric acid and sodium hydrogencarbonate.
149
What happens to the temperature of the surroundings during an endothermic reaction?
Decreases
150
State two uses of exothermic reactions
Self-heating cans, hand warmers
151
State two uses of endothermic reactions
Some cooling sports injury packs
152
What is a reaction profile?
A diagram which shows whether the reactants have more or less energy than the products.
153
(HT) State which of bond breaking and bond making is endothermic and which is exothermic
Breaking: exothermic, making: endothermic
154
(HT) How do we work out the overall energy change of a reaction?
Work out the difference between the energy needed to break all the bonds the reactants and the energy release to form all the bonds in the products.
