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Chemistry > Chapter 7 and 8 - Periodicity > Flashcards

Chapter 7 and 8 - Periodicity Flashcards

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1
Q

What does metallic bond occur in?

A

Metal to metal

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2
Q

What is a giant ionic lattice?

A

A regular arrangement of ions

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3
Q

What are delocalised electrons in terms of metallic bonding?

A

The outer shell electrons of the metals that hold the cations together

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4
Q

What are the properties of metallic bonding?

A

High melting point
High electrical conductivity
Low solubility

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5
Q

Why is melting point high in metallic bonding?

A

Because there is strong electrostatic attraction between the delocalised electrons and ions

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6
Q

Why is electrical conductivity high in metallic bonding?

A

Because the delocalised electrons act as mobile charge carriers as they can move within the structure

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7
Q

Why is solubility low in metallic bonding?

A

Because some metals react with water to form metal hydroxides

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8
Q

How is the periodic table ordered?

A

By atomic number increasing across a period

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9
Q

What are groups?

A

Elements with similar chemical and physical properties

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10
Q

What are periods?

A

Rows that show repeating trends in chemical and physical properties

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11
Q

Define periodicity

A

The trend in properties that show a repeating pattern across different periods

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12
Q

Define ionisiation

A

The formation of positively formed ions

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13
Q

Define first ionisation energy

A

The energy required to remove 1 electron from each atom in 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ions

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14
Q

Give an example of an equation for first ionisation energy

A

Na(g) —-> Na+(g) +e-

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15
Q

What is ionisation energy dependent on?

A

Atomic radius
Nuclear charge
Electron shielding

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16
Q

Explain why the ionisation energy of Be is less than oxygen

A

Because it has a larger atomic radius than oxygen because the nuclear charge is less and that means that nuclear attraction is weaker and less energy is needed to loose an electron from Be than O

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17
Q

Explain the trend in ionisation energy down a group

A

It decreases because atomic radius increases because there are more shells and shielding increases and therefore nuclear attraction decreases so energy required to overcome electrostatic attraction is less

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18
Q

Explain why there is a slight drop in ionisation energy between the 4th and 5th elements in a period

A

Because the electrons start to pair and these will repel. This reduces the energy required to remove an outermost electron and ionisation energy decreases

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19
Q

Explain the trend in successive ionisation energies

A

An increase because the nuclear charge increases as each electron is removed so the electrostatic attraction between the nucleus and the electrons and increases and the energy required to remove the electron

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20
Q

Which elements exist as giant covalent structures?

A

Boron, carbon and silicon

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21
Q

What are the properties of giant covalent structures?

A

Very high melting points
Low electrical conductivity
Insoluble

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22
Q

Why do giant covalent lattices have high melting points?

A

because there are 4 covalent bonds to break so they need a lot of energy to overcome the forces

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23
Q

Why do giant covalent lattices have low electrical conductivity?

A

Because there are no delocalised electrons to carry charge (apart from graphine because they only form 3 c-c bonds so there is one delocalised electrons)

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24
Q

What is a base?

A

A proton acceptor

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25
Q

What does an alkali have in an aqueous solution?

A

free moving OH- ions

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26
Q

Group 2 metals + oxygen —->

Write a general equation for this

A

Metal oxide

2M +O2 —-> 2MO

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27
Q

2M + O2 —-> 2MO

Which is oxidised and which is reduced?

A

The metal is oxidised because it looses electrons 0—> +2

The oxygen is reduced because it gains electrons 0—-> -2

Oxidation is loss of electrons
Reduction is gain of electrons

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28
Q

Group 2 metals + water ——>

Write a general formula for this

A

An alkaline hydroxide and hydogen

M+ 2H20 —-> M(OH)2 + H2

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29
Q

Reactivity between group 2 metals and oxygen and water increases —— the group

A

Down

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30
Q

Group 2 metals + dilute acid —->

Write a reaction for this equation

A

Salt and hydrogen (MASH)

M + 2HCl —-> MCl2 + H2

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31
Q

M + 2HCl —-> MCl2 + H2

Which is oxidised and which is reduced?

A

Metal is oxidised because it loses electrons and the oxidation number goes from 0——> +2
The hydrogen is reduced because it gains electrons and the oxidation number goes from +1 —-> 0

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32
Q

Group 2 hydroxides are only ——- in water

A

Soluble

33
Q

The solubility of the hydroxides in water —— down the group so the resulting solutions contain more ———- and are more —-

A

Increases
OH- ions
Alkaline

34
Q

Explain 2 uses of group 2 compounds as bases

A

Acid reflux which neutralises excess stomach acid

Can be used to neutralise acidic soils which helps plants grow

35
Q

Explain the trends in boiling points for the halogens

A

At room temperature and pressure the halogens exist as diatonic molecules
In their solid state halogens form lattices with simple molecular structures

Boiling points decrease up the group

36
Q

Explain why reactivity decreases down a group

A

Because there are more electrons so there are stronger London forces so more energy is required to break the intermolecular forces and the boiling point increases

37
Q

If a halogen added to an aqueous halide is more more reactive than the halide then 2 things will happen
What two things will happen?

A

The reaction takes place

The solution changes colour

38
Q

On earth elements do not occur in their——- —— and are instead found as ——— ——— ions in the sea of found as ——— deposits combined with ——- or ——

A

Natural state
Stable halide
Salt
Sodium or potassium

39
Q

2NaBr + Cl2 ——> 2NaCl + Br

Explain which is oxidised and which is reduced in this reaction

A

Br is oxidised because it loses electrons and the oxidation number goes from -1—-> 0

Cl is reduced because it gains electrons as the the oxidation number goes from 0 ——-> -1

40
Q

The halogens react in redox by ——- electrons so down the group the tendency to gain an electron ——— as there is more ——- ——— and more a ———- atomic radius so the electrostatic attraction between electrons and protons is ——— so it is more difficult to ——- an electron

A 
Gaining 
Decreases
Electron shielding
Larger
Weaker
Attract
41
Q

What are the colours of Cl precipitates, Br precipitates and I precipitates in solution?

A

Pale green
Orange
Brown

42
Q

What are the colours of Cl precipitates, Br precipitates and I precipitates in cyclohexane?

A

Pale green
Orange
Lilac

43
Q

Why does Br2 change to yellow when old?

A

Because it undergoes radical substitution because homolytic fission occurs and Br ions are not orange so the colour breaks down when exposed to UV light

44
Q

Why does cyclohexane change the colour of iodine from brown to violet?

A

Because forces in cyclohexane are London forges and are weak. The forces in H20 are strong and hydrogen bonds. The forces of Br2 are London forces. So in cyclohexane Br2 becomes violet because like dissolves like and the non-polar halogens dissolve more readily in cyclohexane than water and produce colours that are easier to tell apart

45
Q

Define disproportionation

A

A reaction in which the same element is both oxidised and reduced

46
Q

Write the 2 disproportionation reactions we have to remember

A

Cl2 (aq) + H20 (l) —-> HClO(aq) + HCl (aq)

Cl2(aq) + 2NaOH (aq) —-> NaClO(aq) + NaCl (aq) + H20

47
Q

What are the conditions needed for making bleach?

A

The sodium hydroxide needs to be cold and dilute

48
Q

List the benefit of using chlorine water for making clean drinking water

A

Kills bacteria in water preventing diseases like cholera and typhoid

49
Q

List the risks of using chlorine water for making clean drinking water

A

Chlorine gas could be formed and it is toxic

Chlorine can react with organic hydrocarbons such methane which is carcinogenic

50
Q

How do you test for halide ions?

A

Add aqeuous silver nitrate and the halide would form a precipitate with the silver. Add ammonia to determine which halide is present if it is not clear

51
Q

What precipitates are formed from Cl-, Br- and I- in solution with silver nitrate?

A

AgCl forms a white precipitate
AgBr forms a cream precipitate
AgI forms a yellow precipitate

52
Q

What precipitates are formed from Cl-, Br- and I- in AMMONIA with silver nitrate?

A

AgCl dissolves in any concentration of ammonia
AgBr dissolves but only in concentrates ammonia
AgI doesnt dissolve in ammonia

53
Q

All nitrates are ….

A

Soluble

54
Q

Most halide salts are …..

A

Soluble

55
Q

Most sulfate compounds are ….

A

Soluble

56
Q

Most carbonates are ….

A

Insoluble

57
Q

Which halide salts are insoluble?

A

Ag+ Pb + and Hg2 2+

58
Q

Which sulfate compounds are insoluble?

A

Ba2+ Sr2+ Ca+ Pb+ Hg2 2+ Hg2+ and Ag+

59
Q

Which carbonates are soluble?

A

NH4 and group 7

60
Q

Describe the test for carbonate ions

What is the positive test result?

A

Add dilute nitric acid until effervescence stops to ensure all CO3 2- has reacted off

Effervescence and if passed through lime water it goes cloudy

61
Q

Why should you use nitric acid instead of hydrochloric acid or sulfuric acid in a carbonate test?

A

Because they will release sulfate ions or chloride ions which will give positives for the nexts tests even if chloride or sulfide ions werent originally present

62
Q

What is the formula for a carbonate ion?

A

CO3 2-

63
Q

What is the formula for a sulfate ion?

A

SO42-

64
Q

Describe the test for sulfate ions and what happens if the test is positive

A

A white precipitate is formed when aqeuous barium nitrate is added
It should be filtered out to remove the white precipitate

65
Q

Why can you not use barium chloride for a sulfate test?

A

Because the chloride ions would be released and will give a positive when testing for chlorides

66
Q

What is the formula for an ammonium ion?

A

NH4 +

67
Q

What is the test for ammonium ions ?

What is the positive result?

A

Add NaOH
Heat over a bunsen and test the gas with moist indicator paper
The paper turns blue because ammonium gas is alkaline

68
Q

What is the order of testing for negative ions?

A

Carbonate test
Sulfate
Halide

Ammonium in a different test tube

69
Q

Explain why the sulfate test has to be carried out after the carbonate test

A

Because the Ba of the sulfate test would react with the carbonate ions that havent been reacted off and would make BaCO3 which is insoluble in solution

70
Q

Explain why the halide test needs to be carried out after the carbonate and sulfate tests?

A

Because Ag and CO3 would make a precipitate and Ag and SO4 would make a precipitate so it has to be done after these ions have been reacted off

71
Q

Define periodicity

A

The trend in properties that show a repeating pattern across different periods

72
Q

Define ionisation

A

The formation of positivity formed ions

73
Q

Define first ionisation energy

A

The energy required to remove 1 electron from each atom in 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ions

74
Q

Write the equation showing first ionisation of sodium

A

Na (g) ——> Na+ (g) + e-

75
Q

What 3 factors is ionisation energy dependent on?

A

Atomic radius
Nuclear charge
Electron shielding

76
Q

Explain the trend in ionisation energy across a period

A

There is a general increase because electron shielding remains similar because theyre in the same shell. Atomic radius decreases because shielding remains similar, the nuclear charge increases so nuclear attraction increases which pulls the electrons closer to the nucleus. This increases the electrostatic attraction between the nucleus and the electrons so first ionisation energy increases

77
Q

Explain the trend in first ionisation energy down a group

A

There is a general decrease because the atomic radius increases and electron shielding increases because there are more shells so electrostatic attraction between the nucleus and the electrons decrease

78
Q

Explain the unexpected results in ionisation energies between beryllium to boron

A

There is a fall in ionisation energy between Be and B because it is when the 2p subshell starts filling.
As the 2p subshell is higher in energy than the 2s subshell it requires less energy to remove an electron from it

79
Q

Explain the unexpected result in the ionisation energies of nitrogen to oxygen

A

When the 2p electrons start to pair the paired electrons will repel
This reduced the energy required to remove an outermost electron and the ionisation energy decreases

Chemistry (21 decks)

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