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Edexcel A-Level Chemistry > Chapter 4 - Inorganic chemistry and the Periodic table (L) > Flashcards

Chapter 4 - Inorganic chemistry and the Periodic table (L) Flashcards

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1
Q

What is the definition of first ionisation energy?

A

The energy required to remove an electron from each atom in one mole of atoms in gaseous state

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2
Q

What is the definition of second ionisation energy?

A

The energy required to remove an electron from each 1+ ion in one mole of 1+ ions in gaseous state

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3
Q

What is the base cause of a high or low ionisation energy?

A

A high or low electrostatic attraction between the nucleus and outermost electron

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4
Q

What is electron shielding, and what is its effect on ionisation energy?

A

The idea that inner electrons shield the outer electrons from the electromagnetic pull of nucleus, weakening their attraction.

This hence decreases ionisation energy, as it is not as difficult to remove the outer electron

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5
Q

What are the 3 main factors to consider when explaining trends in ionisation energy?

A
  • Nuclear charge
  • Number of shells
  • Electron shielding
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6
Q

What is the trend in reactivity down group 2?

A

Reactivity increases down the group, as less energy is required to remove the 2 outer electrons as you go down the group (first and second ionisation energy)

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7
Q

What is the trend in the vigorousness of reactions down group 2?

A

As you go down group 2, the reactions become more vigorous

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8
Q

What happens between group 2 elements and oxygen even without heating?

A

A slow reaction occurs, in which a surface coating of oxygen forms around the element, helping prevent further reaction

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9
Q

How is barium often stored and why?

A

Because it is the most reactive, it is often stored under oil to keep it reacting with oxygen and water vapour in the air

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10
Q

What is the general formula for group 2 reactions with oxygen? (M = group 2 element)

A

2M(s) + O2(g) -> 2MO(s)

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11
Q

What is the general formula for group 2 reactions with chlorine? (M = group 2 element)

A

M(s) + Cl2(g) -> MCl2

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12
Q

What is effervescence?

A

Bubbles in a liquid (fizz)

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13
Q

What is seen in the reactions with group 2 elements with water as you go down the group?

A

Increasing effervescence

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14
Q

What is the general formula for group 2 reactions with water? (M = group 2 element)?

A

M(s) + 2H2O(l) -> M(OH)2(aq) + H2(g)

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15
Q

What is the exception to the general formula for group 2 reactions with water?

A

Calcium, which forms a solid rather than aqueous hydroxide- Ca(OH)2 (s)

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16
Q

What is the formula for when Mg is heated in steam?

A

Mg(s) + H2O(g) -> MgO(s) + H2(g)

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17
Q

Why is hydrogen burned as it leaves the tube?

A

So it forms H2O, so there is not a highly flammable gas floating around in the lab

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18
Q

Why is it not a good idea to use water to put out a magnesium fire?

A

Because the magnesium will react with the water, feeding the fire more oxygen and releasing flammable hydrogen gas, which will further feed the fire

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19
Q

What type of oxides are group 2 oxides?

A

Basic oxides

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20
Q

What are basic oxides?

A

Oxides that can react with water to form alkalis

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21
Q

What is the general formula for group 2 oxides reacting with water?

A

MO(s) + H2O(l) -> M(OH)2 (aq)

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22
Q

What is the trend in solubility down group 2?

A

As you go down the group, solubility increases

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23
Q

What is the trend in the alkalinity of solution produced down group 2?

A

As you go down the group the pH (alkalinity) increases

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24
Q

What can be used to test for carbon dioxide?

A 
Calcium hydroxide (limewater)- goes milky as a white precipitate forms.
Calcium reacts with CO2 to form calcium carbonate (white precipitate)
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25
Q

What is milk of magnesia and what does it do?

A

Magnesium hydroxide- it reacts with HCl in the stomach, neutralising it

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26
Q

What do all group two oxides and hydroxides react with acids to form?

A

Salts and water (neutralisation reactions)

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27
Q

Example of how group 2 hydroxides are used in agriculture

A

Calcium hydroxide is used to neutralise excess acidity in soil

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28
Q

What is the solubility of group 2 nitrates and chlorides?

A

All group 2 nitrates and chlorides are soluble

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29
Q

What is the trend in the solubility of group 2 sulfates?

A

The solubility of group 2 sulfates decreases down the group

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30
Q

What solubility is magnesium sulfate classed as?

A

Magnesium sulfate is soluble

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31
Q

What solubility is calcium sulfate classed as?

A

Calcium sulfate is slightly soluble

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32
Q

What solubility is strontium and barium sulfate classed as?

A

Insoluble

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33
Q

How can you use barium ions to test for sulfate ions?

A

A solution containing barium ions can be added, and any sulfate ions will react with the barium ions to form a white precipitate of barium sulfate

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34
Q

Why is an acid also added alongside the barium ions to test for sulfate ions?

A

To prevent barium ions reacting with carbonate ions, which would also form a white precipitate

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35
Q

How and why are barium meals used?

A

Solutions containing barium ions are poisonous to humans, however barium sulfate is insoluble so not poisonous (as the ions cannot move).
Barium meals are used to make soft tissues show up more clearly in x-rays

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36
Q

What is thermal stability?

A

The measure of the extent to which a compound decomposes when heated

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37
Q

What is the difference in thermal stability between group 1 and 2?

A

Group 1 compounds are more thermally stable than group 2 compounds

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38
Q

What are 2 reasons why group 1 compounds are more thermally stable than group 2 compounds?

A
  • Group 2 cations have double the charge

- The ionic radius of group 2 cations is smaller (in the same period)

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39
Q

What is the trend in ionic radius of group 2 cations?

A

As you go down the group, ionic radius increases

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40
Q

What do all group 1 and 2 nitrates decompose to when heated?

A

Nitrites (lesser decomposition) or oxides (greater decomposition)

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41
Q

What are the brown fumes that are given off during the decomposition of nitrates?

A

Nitrogen dioxide

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42
Q

What does brown fumes not being given off indicate?

A

Lesser decomposition

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43
Q

What does brown fumes being given off indicate?

A

Greater decomposition

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44
Q

What is the word equation for lesser decomposition of nitrates?

A

Metal nitrate -> metal nitrite + oxygen

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45
Q

What is the word equation for greater decomposition of nitrates?

A

Metal nitrate -> metal oxide + nitrogen dioxide + oxygen

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46
Q

What type of decomposition occurs in group 2 nitrates, and what does this mean brown fumes wise?

A

All group 2 nitrates have greater decomposition, which means they will give off brown fumes

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47
Q

What type of decomposition occurs in group 1 nitrates, and what does this mean brown fumes wise?

A

Group 1 nitrates have lesser decomposition, which means they will not give off brown fumes.
EXCEPT FOR ONE EXCEPTION- LITHIUM NITRATE

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48
Q

What is the one exception to group 1 nitrates decomposition and why?

A

Lithium nitrate- this is because it is the smallest group 1 cation

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49
Q

What are the two possibilities of decomposition of group 1 and 2 carbonates?

A

They either don’t decompose, or decompose to oxides and give off carbon dioxide

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50
Q

What is the word equation for the decomposition of carbonates?

A

Metal carbonate -> metal oxide + carbon dioxide

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51
Q

Do group 2 carbonates decompose?

A

Yes. All group 2 carbonates decompose to a metal oxide, giving off carbon dioxide

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52
Q

Do group 1 carbonates decompose?

A

No. Group 1 carbonates do not decompose.

EXCEPT FOR ONE EXCEPTION- LITHIUM CARBONATE

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53
Q

What is the one exception to the decomposition of group 1 carbonates and why?

A

Lithium carbonate- this is because it is the smallest group 1 cation

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54
Q

What observations can be made for the decomposition of carbonates and why?

A

No observations can be made.

Both carbonate and oxides are white solids, and carbon dioxide is given off, which is colourless

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55
Q

Why does a greater charge on the cations lead to a lower thermal stability?

A

Because a greater charge will result in a higher level of electron distortion, making it more unstable

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56
Q

Why does a smaller size result in a higher level of distortion?

A

It means the cation will have a higher charge density, which will result in a higher level of electron distortion, making it more unstable

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57
Q

What do flame tests identify?

A

The presence of a cation in a compound

58
Q

What equipment must you use for flame tests?

A
  • Safety glasses
  • Lab coat
  • Fume cupboard
  • Bunsen burner
59
Q

In flame tests, what should you add to the metal compound and why?

A

Concentrated hydrochloric acid, so the metal compound begins to dissolve

60
Q

What type of metal should the metal wire be in flame tests?

A

Platinum or nichrome wires

61
Q

What do you use the metal wire for in flame tests?

A

Dip it into the mixture to obtain a sample of the compound, then hold the end of the wire in the flame and observe the colour

62
Q

What can you use instead of platinum or nichrome wires

A

Silica rods

63
Q

What are the 2 main problems with flame tests?

A
  • Compounds may contain sodium impurities, and the intense colour of sodium may mask other colours
  • Describing colours is subjective, meaning word descriptions of the flame may mean different colours to different people
64
Q

What flame colour is lithium?

A

Red

65
Q

What flame colour is sodium?

A

Yellow/orange

66
Q

What flame colour is potassium?

A

Lilac

67
Q

What flame colour is rubidium?

A

Red/purple

68
Q

What flame colour is caesium?

A

Blue/violet

69
Q

What flame colour is beryllium?

A

No colour

70
Q

What flame colour is magnesium?

A

No colour

71
Q

What flame colour is calcium?

A

Brick red

72
Q

What flame colour is strontium?

A

Crimson red

73
Q

What flame colour is barium?

A

Apple green

74
Q

Why is concentrated hydrochloric acid used in flame tests?

A

Conc. HCl converts the compounds into their metallic chlorides, which is important because, the metallic chlorides are very much volatile, so are more likely to give stronger results

75
Q

What causes the colours in a flame test to appear?

A

When electrons absorb energy, they move to higher energy levels, and then back down again. This releases energy- if this energy corresponds to radiation in the visible light spectrum, then a flame test colour appears.

76
Q

What is the ground state of an atom?

A

When an atom has all its electrons in their lowest possible energy levels

77
Q

What is the excited state of an atom?

A

When an atom gains energy and moves to a higher energy level

78
Q

What is the test for ammonium ions?

A

Warm with sodium hydroxide- releases ammonia gas

79
Q

How can you test for the presence of ammonia gas?

A
  • Damp red litmus paper turns blue

- Reacts with hydrogen chloride gas to form white fumes (ammonia chloride)

80
Q

What are the group 7 elements known as?

A

Halogens

81
Q

What is the general trend in melting point down group 7?

A

As you go down group 7, the melting point increases

82
Q

What elements are gas at room temperature in group 7?

A

Fluorine and chlorine

83
Q

What elements are liquid at room temperature in group 7?

A

Bromine

84
Q

What elements are solid at room temperature in group 7?

A

Iodine and astatine

85
Q

What determines the melting temperature of group 7 elements?

A

The strength of the London forces between molecules

86
Q

Why does the strength of the London forces increase down group 7?

A

As you go down group 7, the number of electrons increases. More electrons = bigger/more polar instantaneous dipoles = bigger/more polar induced dipoles = greater strength of electromagnetic attraction between the dipoles

87
Q

What is sublimation, and what group 7 element does it happen to?

A

Sublimation is where a solid turns directly into a gas. This happens to iodine

88
Q

What is the trend in electronegativity in group 7?

A

As you go down the group, electronegativity decreases

89
Q

Why does electronegativity decrease down group 7?

A

As you go down the group, both the atomic radius and amount of electron shielding increase, meaning there is a greater distance between the nucleus and bonding pair electrons and a weaker electrostatic attraction.

90
Q

What is electron shielding?

A

The idea that electrons in inner shells shield the outer shell from the pull of the nucleus, causing the outer electrons to feel a weaker, shielded nuclear attraction

91
Q

What is the trend in reactivity down group 7?

A

As you go down the group, reactivity decreases

92
Q

Why does reactivity decrease down group 7?

A

Because atomic radii increases. Greater distance from positive nuclei = less positive attraction = harder to attract and gain an electron

93
Q

What is the trend in the oxidising power of halogen molecules down group 7?

A

As you go down the group, oxidising power decreases

94
Q

What is the trend in the reducing power of halide ions down group 7?

A

As you go down the group, reducing power increases

95
Q

What does bromine displace?

A

Iodine but not chlorine

96
Q

What does chlorine displace?

A

Iodine and bromine

97
Q

What does iodine displace?

A

Neither chlorine nor bromine

98
Q

What does it mean to have a strong oxidisation power?

A

It can easily oxidise the other thing (a good oxidising agent) i.e. is good at gaining electrons

99
Q

What is disproportionation?

A

Where a substance is both oxidised and reduced in the same reaction

100
Q

Why are iodide ions better reducing agents than chloride ions?

A

There is a weaker attraction in iodide ions between the outer electrons and the nucleus (due to the larger size), so iodide ions can more easily lose an electron, making it a better reducing agent

101
Q

What does it mean to have a strong reducing power?

A

It can easily lose electrons, and hence reduce the other thing (a good reducing agent)

102
Q

What observation will you see when you add (sodium) chloride to sulfuric acid?

A

Misty fumes

103
Q

What products are formed when you react (sodium) chloride with sulfuric acid?

A

Hydrogen chloride (HCl)

104
Q

What happens when you react (sodium) bromide with sulfuric acid?

A

Initially, hydrogen bromide is produced.

However the HBr produced then reacts with the sulfuric acid again, producing Br2 and sulfur dioxide

105
Q

Why is only hydrogen chloride produced when you add (sodium) chloride to sulfuric acid?

A

Because it’s not a strong enough reducing agent to reduce the sulfuric acid

106
Q

Is reacting (sodium) bromide with sulfuric acid a redox reaction?

A

Initially no.
However, as the HBr goes on to react with the sulfuric acid, that is a redox reaction, as the sulfuric acid is reduced and the Br oxidised

107
Q

What observation will you see when you add (sodium) bromide to sulfuric acid?

A

Hydrogen bromide = misty fumes
Bromine = brown fumes
Sulfur dioxide = choking smell

108
Q

What happens when you react (sodium) iodide with sulfuric acid?

A

Everything that happened in the bromide + sulfuric acid reaction, but then one step further.
The HI will then react with the sulfur dioxide produced, forming hydrogen sulfide.
Sulfur is also produced.

109
Q

What is produced when you react (sodium) iodide with sulfuric acid?

A 
Hydrogen iodide = misty fumes
Iodine = purple fumes
Sulfur dioxide = choking smell
Sulfur = yellow solid
Hydrogen sulfide = rotton egg smell
110
Q

What is produced when you react hydrogen bromide/iodide with sulfuric acid?

A

Hydrogen bromide/iodide + sulfuric acid -> sulfur dioxide + water + bromine/iodine

111
Q

Overall, what happens in the reaction between bromide and sulfuric acid?

A

Bromide ions reduce the sulphuric acid to sulphur dioxide. In the process, the bromide ions are oxidised to bromine

112
Q

Overall, what happens in the reaction between iodide and sulfuric acid?

A 
Iodide reduces the sulfuric acid:
first to sulphur dioxide
then to sulphur itself
and all the way to hydrogen sulphide.
The iodide ions are oxidised to iodine
113
Q

What is are some problems in interpreting colour changes in group 7 displacement reactions?

A

The similarity of colours between group 7 elements

Colour variation dependent on concentration

114
Q

Why is it a good idea to add an organic solvent like cyclohexane after group 7 displacement reactions?

A

Halogens are more soluble in cyclohexane than water, so the halogen dissolves in the organic layer, where its colour can be more easily seen

115
Q

What is the reaction between chlorine and water an example of?

A

Disproportionation, as the chlorine is both oxidised and reduced

116
Q

What are the two products from the reaction between chlorine and water?

A

HCl + HClO

117
Q

What is the difference when chlorine is reacted with hot compared to cold alkali?

A

When chlorine is reacted with cold alkali, it forms sodium chlorate (I), whereas when chlorine is reacted with hot alkali, it forms sodium chlorate (V)

118
Q

What is the purpose of adding chlorine to water?

A

Disinfects water by killing pathogens

119
Q

What is sodium chlorate (I) used as?

A

It is the active ingredient in household bleach

120
Q

What is sodium chlorate (V) used as?

A

It is also used in bleaching, and as a weed killer

121
Q

In testing for halides in solution, why is nitric acid used beforehand?

A

To make sure any other anions (in particular carbonate ion) are removed, as they would otherwise also form precipitates

122
Q

Why do we need to test for halides in solution?

A

They are colourless so indistinguishable

123
Q

What can you observe when you add silver nitrate to a fluoride solution?

A

There is no visible change- this is because silver fluoride is soluble

124
Q

What can you observe when you add silver nitrate to a chloride solution?

A

A white precipitate will be formed

125
Q

What can you observe when you add silver nitrate to a bromide solution?

A

A cream precipitate will be formed

126
Q

What can you observe when you add silver nitrate to an iodide solution?

A

A yellow precipitate will be formed

127
Q

Why do we after adding silver nitrate, add dilute aqueous ammonia and concentrated aqueous ammonia?

A

As after just adding the silver nitrate, it might be difficult to clearly distinguish which colour the precipitate is i.e what halide is present. So further tests are done to fully prove which halide is present

128
Q

Which halide precipitate disappears after the addition of dilute aqueous ammonia?

A

(Silver) chloride

129
Q

Which halide precipitates do not disappear after the addition of dilute aqueous ammonia?

A

(Silver) bromide and iodide

130
Q

Which halide precipitate disappears after the addition of concentrated aqueous ammonia?

A

(Silver) bromide. (Silver chloride would also disappear however it should already be gone from the addition of dilute aqueous ammonia)

131
Q

Which halide precipitate should remain present throughout the addition of both dilute and concentrated aqueous ammonia?

A

(Silver) iodide

132
Q

What is the general ionic equation for the formation of the precipitates?

A

Ag+(aq) + X-(aq) –> AgX(s)

133
Q

What is the difference between hydrogen chloride and hydrochloric acid?

A

Hydrogen chloride is a gas.

Hydrochloric acid is aqueous

134
Q

What acid is formed when hydrogen fluoride is added to water?

A

Hydrofluoric acid

135
Q

What acid is formed when hydrogen chloride is added to water?

A

Hydrochloric acid

136
Q

What acid is formed when hydrogen bromide is added to water?

A

Hydrobromic acid

137
Q

What acid is formed when hydrogen iodide is added to water?

A

Hydriodic acid

138
Q

What is the general equation for the reaction of hydrogen halide + water?

A

HX + H2O –> X- + H3O+

139
Q

How is hydrofluoric acid different to the other halide acids?

A

It is a weak acid. In the reaction between HF + H2O is reversible

140
Q

What happens when hydrogen halides react with ammonia gas?

A

A white ionic salt is formed

141
Q

What is the general equation for the reaction between ammonia gas and hydrogen halides?

A

NH3(g) + HX(g) –> NH4X(s)

142
Q

How do you react ammonia gas and hydrogen halides (e.g. chloride)?

A

You soak cotton wool pieces in concentrated aqueous ammonia and concentrated hydrochloric acid respectively, and put them in a tube.
The cotton wool pieces will give off ammonia and hydrogen chloride gas, which will move through the tube to meet and form the white salt ammonium chloride.

Edexcel A-Level Chemistry (24 decks)

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