3.1

Question 1

Periodic trend in electron configuration

Answer 1

Across period: each period starts w an e- in a new highest energy level

Down a group: same no e- in outer shell and in each sub shell. Giving them similar chemistry

Blocks: corresponding to their highest energy sub shell:s,p,d,f

Question 2

Group 2

Answer 2

Trend down group:
• 1st ionisation energy decreases
• reactivity increases
• mpt decreases (atomic radius increases)

Redox reactions: oxygen, water, acids

Question 3

Solubility of Group 2 hydroxides

Answer 3

Solubility increases down the group (as does pH)

Question 4

Halogens

Answer 4

Trend down group:
• reactivity decreases (bigger atomic radius, more shielding, smaller nuclear attraction)
• bpt increases (more e- = stronger London)

Question 5

Ionisation energy

Answer 5

IE measures how easily an atom loses e- to form +ve ions

Factors affecting IE:
• Atomic radius
• Nuclear charge
• Electron shielding

Question 6

1st ionisation energy = ?

Answer 6

Energy required to remove one electron from each atom in one mole of gaseous atoms of an element to form one mole of gaseous 1+ ions

Question 7

2nd ionisation energy = ?

Answer 7

Energy required to remove one electron from each ion in one mole of gaseous 1+ ions of an element to form one mole of gaseous 2+ ions

Question 8

Successive ionisation energies

Answer 8

Allow predictions to me made about:
• no of e- in outer shell
• group of the element
• the identity of an element

Question 9

Trends in 1st ionisation energies across period

Answer 9

General increase across each period

A sharp decrease between end of one period and the start of the next

Question 10

Trends in 1st ionisation energy down a group

Answer 10

Decreases down a group bc although nuclear charge increases, this is outweighed by the increased radius and increased shielding

Question 11

Periodic trend in melting points

Answer 11

Mpt increases from G1 to G14

Sharp decrease mpt G14 to G15 (from giant covalent to simple molecular)

Low mpt G15 to G18

Question 12

Changes in structure across P2 and P3

Answer 12

Giant metallic
to
Giant covalent structure 
to
Simple molecular structure

Question 14

Metallic bonding

Answer 14

Pool of delocalised electrons

Strong electrostatic attraction between cations (+ve) and delocalised e-

Cations fixed in position

e- mobile = high electrical conductivity

Insoluble

Question 15

Disproportionation

Answer 15

Same element is both oxidised and reduced

e.g. chlorine and water
Cl2 + H2O -> HClO + HCl

e.g. chlorine and cold dilute aqueous sodium hydroxide
Cl2 + 2NaOH -> NaClO + NaCl + H2O

Question 16

Halogens: why Chlorine is beneficial

Answer 16

Kills bacteria = safe drinking water

However:
Chlorine could react with organic compounds = carcinogenic chemicals (chlorinated hydrocarbons)

Question 17

Carbonate test

Answer 17

Add nitric acid

CO2 has produced = carbonate present (bubbles)

Question 18

Sulfate test

Answer 18

Add barium ions

White BaSO4 precipitate = sulfate ions

Question 19

Giant covalent structures and properties

Answer 19

Non-metals boron, carbon, silicon

High mpt bpt (strong covalent bonds)
Insoluble
Non-conductors (except graphene and graphite)

Question 20

Ammonium ion test NH4+

Answer 20

Ammonium ions + hydroxide ions -> ammonia gas + water

NH4+ + OH- -> NH3 + H2O

Question 22

Test for halide ions

Answer 22

Ag+ + X- -> AgX (s)

Add silver nitrate

Chloride = white (soluble in dilute NH3)
Bromide = cream (soluble in conc. NH3)
Iodide = yellow (insoluble in NH3)