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Chemistry Paper 1 > Module 3 > Flashcards

Module 3 Flashcards

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1
Q

How did Mendeleev arrange the 60 known elements? (2 mark)

A

By atomic mass, and in groups with similar properties.

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2
Q

What 3 things did Mendeleev do that made the periodic table more similar to the one we have today? (3 marks)

A

If the group properties did not fit, he swapped the elements around.
Left gaps for undiscovered elements.
He predicted properties of the missing elements from the group trends.

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3
Q

What are the elements arranged in now? (1 mark)

A

Atomic number

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4
Q

What is periodicity? (1 mark)

A

When there is a repeating trend in properties of the elements across a period.

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5
Q

Where is the s block on the periodic table? (1 mark)

A

Groups 1 and 2

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6
Q

Where is the p block on the periodic table? (1 mark)

A

Groups 3-12

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7
Q

Where is the d block on the periodic table? (1 mark)

A

Groups 13-18

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8
Q

What group did Mendeleev omit entirely, and why he was unaware of it? (2 marks)

A

Noble gases, group 18, group 0, group 8
They are unreactive

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9
Q

What is ionisation energy? (1 mark)

A

Ionisation energy measures how easily an atom loses electrons to form positive ions.

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10
Q

What three factors affect ionisation energy? (3 marks)

A

Atomic radius
Nuclear charge
Electron shielding

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11
Q

What energy does the first electron lost have? (1 mark)

A

Is on the highest energy level.

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12
Q

How does atomic radius affect ionisation energy? (2 marks)

A

The greater the distance between the nucleus and the outer electrons the less the nuclear attraction. Therefore the ionisation energy decreases.

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13
Q

How does nuclear charge affect ionisation energy? (2 marks)

A

The more protons there are in the nucleus of an atom, the greater attraction between the nucleus and outer electrons. Therefore the ionisation energy increases.

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14
Q

How does electron shielding affect ionisation energy? (2 marks)

A

Electrons are negatively charged so the inner-shell electrons repel the outer-shell electrons.
This repulsion reduces the attraction between the nucleus and the outer electrons. Therefore the ionisation energy decreases.

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15
Q

What is the general trend for ionisation energies in periods? (1 mark)

A

A general increase.

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16
Q

Why does boron have a lower first ionisation energy than beryllium? (4 marks)

A

The 2p electron in boron
has a higher energy than
one of the 2s electrons in beryllium,
so it requires less energy to be removed (easier to remove).

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17
Q

Why does oxygen have a lower first ionisation energy than nitrogen? (4 marks)

A

In oxygen, all the electrons in the 2p sub-shell are paired, so one of the paired electrons is removed.
In nitrogen, there is a lone electron in the 2p sub-shell, so this electron is removed first.
The paired electrons repel each other (in oxygen), so an electron is easier to remove from an oxygen atom.
Therefore the first ionisation energy of an oxygen atom is lower than the first ionisation energy of a nitrogen atom.

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18
Q

Why is there a significant drop in first ionisation energy from neon to sodium? (4 marks)

A

The highest energy electron in neon is in the 2p subshell.
The highest energy electron in sodium is in the 3s subshell.
The 3s electron has a higher energy than 2p, so it is a lot easier to remove,
therefore the first ionisation energy for sodium is a lot lower than neon’s.

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19
Q

Why does neon have a higher first ionisation energy than fluorine? (4 marks)

A

Neon’s outer shell is full, causing the first ionisation energy to rise significantly.
It also has more electrons, that are attracted to the nucleus, making neon slightly smaller than fluorine, which means more energy is requisites to remove an electron.

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20
Q

Why does aluminum have a lower first ionisation than magnesium? (4 marks)

A

The highest energy electron in magnesium is in the 3s subshell.
The highest energy electron in aluminum is in the 3p subshell.
The 3p subshell has a higher energy than the 3s subshell,
so the first electron is easier to remove in aluminum,
therefore it has a lower first ionisation energy than magnesium.

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21
Q

Why does sulphur have a lower first ionisation energy than phosphorous? (4 marks)

A

None of the electrons in the 3p subshell in phosphorous are paired.
2 of the electrons in the 3p subshell in sulphur are paired,
so they repel each other,
this makes it easier to remove one of them,
therefore the first ionisation energy is lower in sulphur than in phosphorous.

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22
Q

Trend across groups 2 and 3

Explain the 2, 3, 3 rule.

A

The ionisation energies in the period go up for 2 elements, then down a bit, then up for 3 elements then down a bit, then up for 3 elements (to make a zigzag), then drops back to where the first element was for the new period.

                                  x <-- noblegas
                                /
                            x
                 x       /
                 /\    /
               /    \x
             x
  x       /
  /\    /
/    \x x <-- first element of the period
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23
Q

State and explain the trend in first ionisation energies down a group. (4 marks)

A

Going down a group, the atomic radius increases,
there are more inner shells, so shielding increases,
therefore nuclear attraction to outer electrons decreases,
so the first ionisation energy decreases.

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24
Q

What state are all metals at RTP. except one (name the exception)?
(2 marks)

A

Solid, apart from mercury.

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25
Q

What is metallic bonding? (2 marks)

A

Strong electrostatic attraction between cations and delocalised electrons.

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26
Q

Why do simple molecular structures have low melting and boiling points? ( 2 marks)

A

They have weak induced dipole-dipole interactions (intermolecular forces).
So little energy is needed to overcome these.

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27
Q

What 3 elements form giant covalent lattice, in period 2 and 3? (2 marks)

A

Carbon and silicon and boron

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28
Q

How many nitrogen atoms are in a molecule? ( 1mark)

A

2

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29
Q

How many atoms are in a molecule of phosphorous? (1 mark)

A

4

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30
Q

How many atoms are in a sulphur molecule? (1 mark)

A

8

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31
Q

Why are diamond and silicon non-conductors of electricity? (2 marks)

A

All 4 outer shell electrons are involved in covalent bonding,
so none are available for conducting electricity.

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32
Q

What structure and bond angle do diamond and silicon form? (2 marks)

A

tetrahedral
109.5 degrees

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33
Q

Which elements have a simple molecular structure, in periods 2 and 3? (1 mark)

A

All the elements to the right of carbon.

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34
Q

Describe the graph for the trend in melting points of period 2. (3 marks)

A

Increases across the period until carbon.
Sharp drop (lower than first element in period).
Remaining elements have really low melting points too.

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35
Q

Describe the graph for the trend in melting points of period 3. (3 marks)

A

Increases until silicon.
Sharp drop (lower than first element in period).
Gradual decrease for remaining elements.

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36
Q

Why can ionic compounds conduct electricity when molten? (2 marks)

A

The ionic lattice collapses
So the ions are now able to move and conduct electricity

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37
Q

What is similar (in terms of electron configuration) about the elements in group 2? (1 mark)

A

All have 2 electrons in an outer ‘s’ orbital.

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38
Q

Does the atomic radius increase or decrease as you go down group 2? (1 mark)

A

Increase

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39
Q

Describe and explain the trend in ionisation energies in group 2. (4 marks)

A

Outer electrons are less tightly held my nucleus as go down group,
due to extra shielding from filled shells
and increased repulsion between electrons.
This means less energy is needed to remove outer electrons,
so ionisation energies decrease.

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40
Q

Describe and explain the trend in melting points in group 2. (4 marks)

A

Outer electrons are less tightly held my nucleus as go down group,
due to extra shielding from filled shells
and increased repulsion between electrons.
This means less energy is required to break bonds,
so melting points decrease.

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41
Q

How do group 2 metals react with oxygen? ( 2marks)

A

Forms a metal oxide with the general formula MO.

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42
Q

How do group 2 metals react with water? (3 marks)

A

Forms an alkaline hydroxide, with general formula M(OH)2, and hydrogen gas.

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43
Q

How do group 2 metals react with dilute acids? (2 marks)

A

Redox reaction
Forms a salt + hydrogen gas

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44
Q

How do group 2 oxides react with water? (2 marks)

A

release OH- ions
Form alkaline solutions of the metal hydroxide

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45
Q

What is the trend in solubility of the hydroxides in group 2? (3 marks)

A

Increases as go down group
The resulting solutions contain more OH- ions,
and are more alkaline.

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46
Q

What is one use of the group 2 compounds in agriculture? (2 marks)

A

Calcium hydroxide is added to fields as lime by farmers, to increase the pH of acidic soils.

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47
Q

State two uses of group 2 compounds in medicine. (2 marks)

A

Antiacids- treat indigestion
BaSO4 used in a barium meal (because absorbs xrays well)

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48
Q

What are the elements in group 7 called? (1 mark)

A

The halogens

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49
Q

What is the electron configuration of an element in group 7? (1 mark)

A

All have 7 electrons in their outer shell.

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50
Q

Describe (colour and state) he first 4 elements in group 7, at RTP. (8 marks)

A

F- pale yellow/green gas
Cl- yellow-green gas
Br- red-brown liquid
I- shiny grey solid/ purple vapour

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51
Q

What is the trend in boiling points in group 7, and why? (4 marks)

A

As go down group, the atoms have more electrons, so there are stronger induced dipole-dipole interactions, which means more energy is required to overcome them, this means the boiling point increases.

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52
Q

What is the trend in atomic radius in group 7, why? (2 marks)

A

Increase as go down group, because there are more electron shells (more shielding).

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53
Q

What is the trend in electronegativity in group 7, why? (2 marks)

A

Decrease as go down group, because the attraction of the nucleus to the valent electrons decreases (due to larger atomic radius).

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54
Q

What is the chemical test for halide ions? (2 marks)

A

Add nitric acid + silver nitrate
Positive results:
Cl- white
Br- cream
I- yellow

55
Q

After using nitric acid and silver to test for halides, how do we further distinguish them? (3 marks)

A

Add dilute NH3:
AgCl dissolves

Add concentrated NH3:
AgBr dissolves

AgI is insoluble in both

56
Q

What can be added to halide displacement reactions to make the colour change more obvious? (1 mark)

A

An organic solvent ( like hexane)

57
Q

What is the common name sodium chlorate? (1 mark)

A

Bleach

58
Q

What is disproportionation? (1 mark)

A

Redox reaction where the same element is both oxidised and reduced.

59
Q

What are the benefits and risks of using chlorine to treat water? (3 marks)

A

Benefits:
Kills bacteria

Risks:
Can irritate respiratory system
Cl can react with hydrocarbons in water to create chlorinated hydrocarbons (many of these are carcinogenic).

60
Q

What is the trend in reactivity of group 7, why? (4 marks)

A

As go down group, atomic radius increases, which means there is more shielding, and less nuclear attraction to capture an electron from another species, this means the halogens get less reactive as you go down the group.

61
Q

What are the products when chlorine and water react? (1 mark)

A

HClO and HCl

62
Q

Are group 7 elements oxidising or reducing agents? (1 mark)

A

Oxidising

63
Q

What is a displacement reaction? (1 mark)

A

When an ion displaces a less reactive ion.

64
Q

What is trend in bond enthalpies in group 7? (4 marks)

A

Generally, as go down group:
- atomic radius increases
- valent electrons and bonding pair gets further away from nuclei
- so attraction decreases
- so bond enthalpies decrease

65
Q

Why is the bond enthalpy for F2 lower than for Cl2? (exception to the rule)
(4 marks)

A
  • F2 is a smaller molecule
  • so the electrons in F2 are closer to the outer shell’s unbonded electrons
  • they repel more
  • the extra repulsion makes the F-F bond weaker and easier to break
66
Q

What is the test for carbonate ions? (2 marks)

A

Dilute acid
Positive result: fizzing

67
Q

What is the test for sulphate ions? (2 marks)

A

BaNO3
Positive result: white precipitate

68
Q

What is the test for ammonium ions? (3 marks)

A

NaOH + heat gradually + hold litmus paper above
Positive result: litmus paper turning blue

69
Q

What test distinguishes between Mg2+, Ba2+ or K+ ions? (3 marks)

A

NaOH or KOH + chill
If Mg2+ ions are present: white precipitate

70
Q

What is the test for OH- ions? (1 mark)

A

Litmus paper turns blue

71
Q

What test distinguishes between Ba2+ and K+ ions? (2 marks)

A

H2SO4
If Ba2+ present: white precipitate

72
Q

What does ∆H mean? (1 mark)

A

Heat energy change in constant pressure.

73
Q

What does ∆Hᶱ mean? (1 mark)

A

Heat energy change in standard conditions.

74
Q

What are the standard conditions? (2 marks)

A

101kPa and 298K

75
Q

What are the units for enthalpy change? (1 mark)

A

KJmol-1

76
Q

In an exothermic reaction, are the reactants or products higher? (1 mark)

A

Reactants

77
Q

What are the two axis on an enthalpy profile diagram? (3 marks)

A

Enthalpy (KJmol-1)
Reaction progress

78
Q

Define activation energy. (2 marks)

A

Minimum energy needed to begin breaking bonds and start the chemical reaction.

79
Q

What is the symbol for activation energy? (1 mark)

A

Ea

80
Q

What is enthalpy of reaction? (2 marks)

A

∆H when molar amounts of reactants as stated in the equation react under standard conditions.

81
Q

What is the symbol for enthalpy of reaction? (1 mark)

A

∆rHᶱ

82
Q

What is enthalpy of formation? (2 marks)

A

∆H when one mole of a substance is formed under standard conditions.

83
Q

What is the symbol for enthalpy of formation? (1 mark)

A

∆fHᶱ

84
Q

What is enthalpy of combustion? (2 marks)

A

∆H when one mole of a substance is completely burnt (in oxygen) under standard conditions.

85
Q

What is the symbol for enthalpy of combustion? (1 mark)

A

∆cHᶱ

86
Q

What is enthalpy of neutralisation? (2 marks)

A

∆H when one mole of water is formed when an acid and alkali react under standard conditions.

87
Q

What is the symbol for enthalpy of neutralisation? (1 mark)

A

∆neutHᶱ

88
Q

What is the equation for enthalpy change? (4 marks)

A

Heat given out = mass of substance heated x specific heat capacity x change in temperature

q= mc∆T

89
Q

What are the units in the equation for enthalpy change? (4 marks)

A

q- J
m- g
c- Jg-1k-1
T- K or degrees

90
Q

How can you measure ∆H in combustion reactions? (3 marks)

A

Flammable liquid is burnt inside a flame calorimeter.
The fuel, in a bottle with wick, is burned so that it heats a known mass of water.
The change in temperature of the water is measured.

91
Q

What are 3 possible problems with how we measure ∆H in combustion reactions? ( 3 marks)

A

Incomplete combustion (less energy given out)
Evaporate
Heat loss to surroundings

92
Q

How can you measure ∆H for reactions in solution? ( 2 marks)

A

Reaction carried out in an insulated beaker and change in temperature is measured.

93
Q

Name three possible problems with how we measure ∆H for reactions in solutions? (3 marks)

A

Heat absorbed by container
Heat lost to surroundings
The specific heat capacity is assumed to be 4.185Jg-1k-1

94
Q

What is bond enthalpy? (2 marks)

A

The energy required to break a covalent bond in the gaseous state. Endothermic. (+)

95
Q

What is average bond enthalpy? ( 2marks)

A

One mole of covalent bonds is broken in the gas phase averaged over several different conditions.

96
Q

How do you figure average bond enthalpy? ( 2 marks)

A

∆H of reactants - ∆H of products
or Hess’ cycles

97
Q

What is Hess’ law? (1 mark)

A

Total enthalpy change for a reaction is independent of the route taken (same conditions).

98
Q

What are the two ‘shortcut’ equations for ∆fHᶱ and ∆cHᶱ? (2 marks)

A

∆H = ∑∆fH products - ∑∆fH reactants

∆H = ∑∆cH reactants - ∑∆cH products

99
Q

What is the ∆fHᶱ of elements? (1 mark)

A

0

100
Q

How do you calculate rate of reaction? (1 mark)

A

Measure change in concentration over time.

101
Q

How do you increase the rate of a reaction (according to collision theory)? (1 mark)

A

Need more frequent and successful collisions.

102
Q

How does increasing concentration affect the rate of reaction and why? (3 marks)

A

Increases because the number of particles in a given volume increases, meaning there are more frequent collisions, which in turn increases the number of successful collisions.

103
Q

How does increasing pressure affect the rate of reaction and why? (3 marks)

A

Increases because the number of particles in a given volume increases, meaning there are more frequent collisions, which in turn increases the number of successful collisions.

104
Q

How does increasing surface area of reactants affect the rate of reaction and why? (3 marks)

A

Increases, because more particles are exposed, which means collisions are more frequent.

105
Q

Describe what happens to rate of the reaction as time passes? (3 marks)

A

As time proceeds, reactants get used up so there are less frequent collisions and the rate of reaction decreases.

106
Q

Why are only some collisions effective? (3 marks)

A

The particles need to collide at the correct orientation and have enough energy to overcome the ‘activation barrier’ of the reaction.

107
Q

What is a catalyst?

A

A substance that changes the rate of a chemical reaction without undergoing any permanent change itself.

108
Q

How do catalysts increase the rate of chemical reaction? (1 mark)

A

Provide an alternate reaction pathway with a lower Ea.

109
Q

How do catalysts alter the position of equilibrium? (1 mark)

A

No effect.

110
Q

What is a homogenus catalyst? (3 marks)

A

Is the same physical state as the reactants, and reacts with the reactants to form an intermediate (which then breaks down and the catalyst is regenerated).

111
Q

What is a heterogenus catalyst? (1 mark)

A

Is a different physical state of reactants.

112
Q

Name 3 economic benefits of catalysts. (3 marks)

A

Lower operating temperatures and pressures.
Can improve properties.
Decreases time.
Exothermic reactions- allow reasonable yield in a reasonable amount of time.

113
Q

Name 3 environmental benefits of catalysts. (3 marks)

A

Save energy and decreases carbon dioxide emissions.
Allows alternative reactions with a higher atom economy.
Used in catalytic converters (in cars).

114
Q

What is the Boltzmann distribution? (1 mark)

A

The spread of molecular energies in gases.

115
Q

What does the area under the Boltzmann distribution show? (1 mark)

A

Total number of molecules

116
Q

Why does the Boltzmann distribution curve never meet the x-axis? (1 mark)

A

Because there is no maximum energy.

117
Q

What effect does an increase in temperature have on the Boltzmann distribution curve? (3 marks)

A

The average energy of molecules increases,
which means more collisions are successful and lead to a reaction,
so the curve flattens out so more area is past the Ea line.

118
Q

How does a decrease in temperature affect the Boltzmann distribution curve? (2 marks)

A

Makes the peak higher and the area past the Ea line decreases.

119
Q

How does a catalyst affect the graph for Boltzmann distribution? (1 mark)

A

Moves the Ea to the left (so more are is past the past the Ea line).

120
Q

Why does the Boltzmann distribution curve start at (0,0)? (1 mark)

A

No particles has no energy.

121
Q

What happens if you double the concentration of the reactants? (1 mark)

A

Double the amount of products produced.

122
Q

What is dynamic equilibrium? (1 mark)

A

Rate at which the forward reaction is the same as the reverse reaction.

123
Q

How does increasing temperature affect the position of equilibrium? (1 mark)

A

Moves it towards the endothermic reaction (to try and decrease the temperature).

124
Q

How does increasing concentration affect the position of equilibrium? (1 mark)

A

Moves it towards the side of the reaction you didn’t increase the concentration of.

125
Q

How does increasing pressure affect the position of equilibrium? (1 mark)

A

Moves it towards the reaction which produces less molecules (to try and decrease the pressure).

126
Q

What is the equilibrium constant? (1 mark)

A

(C^c x D^d)/(A^a xB^b)
When aA + bB –><– cC + dD

127
Q

What does am equilibrium constant of 1 mean? (1 mark)

A

That equilibrium is halfway between the reactants and the products.

128
Q

What does am equilibrium constant of 1< mean? (1 mark)

A

That the equilibrium is towards the products.

129
Q

What does am equilibrium constant of 1> mean? (1 mark)

A

That the equilibrium is towards the reactants.

130
Q

What is the contact process? (1 mark)

A

The production of sulphuric acid.

131
Q

What catalyst is used in the contact process? (1 mark)

A

Vandium oxide (V2O5)

132
Q

What is the balanced equation for the reversible reaction in the contact process? (3 marks)

A

2SO2 (g) + O2 (g) –><– 2SO3 (g)

133
Q

What is included in the calculations for Kc in homogeneous reactions? (1 mark)

A

They are all the same physical state so all the reactants and products are included.

134
Q

What is included in the calculations for Kc in heterogeneous reactions? (1 mark)

A

There are different physical states, only gases and aqueous substances are included.

Chemistry Paper 1 (3 decks)

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