Periodicity

Question 1

Ionisation energy

Answer 1

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

Question 2

Factors affecting ie

Answer 2

Atomic radius-greater less energy req
Nuclear charge- more protons more energy required
Electron shielding- inner shell repel outer shell increase radius less energy

Question 3

Successive ionisation energies

Answer 3

Large increase in ie suggests the number of electrons in its outer shell
Due to the shielding being less and smaller radius

Question 4

Ionisation energy group

Answer 4

Decreases down a group
Atomic radius incr
Shielding increases
Nuclear attraction decreases

Question 5

Ionisation energy across a period

Answer 5

Increases
Nuclear charge incr
Nuclear attraction incr
Atomic radius decrease

Question 6

Falls in ie across a period

Answer 6

Group 3 and group 6
3= filling 2p sub shell easier to remove from p than 2s
6= paired electron in a 2p orbital repel each other easier to remove than single electron

Question 7

Periodic trend in melting points

Answer 7

Across period increase form group 1 to 4 (giant structures metallic/covalent)
Sharp decrease from 4 to 5 (drop to simple molecular)
5 to 8 low mp

Question 8

Group 2 reactions

Answer 8

Reducing agent (lose 2e-)
Redox with oxygen forming oxide
Redox with water forms hydroxide
Redox w dilute acid (metal salt)

Question 9

Group 2 reactivity trend and ie

Answer 9

IE decreases down the group
More reactive and stronger reducing agents down the group

Question 10

Reaction of group 2 compounds

Answer 10

Oxides react with H2O form hydroxide ions
When saturated form hydroxides
Solubility of these hydroxides increase down group as well as pH

Question 11

Uses of group 2 compounds

Answer 11

Hydroxides Ca(OH)2 added to field to increase pH of acidic soils
Group 2 bases used as antacids for indigestion mainly carbonates are used
Mg(OH)2 is sometimes used

Question 12

Halogen trends

Answer 12

Boiling point increases down group due to more electrons so stronger London forces

Question 13

Reactions of halogens

Answer 13

Redox reactions lose 1e- from atom oxidising agent
Displacement reactions

Question 14

Displacement reactions

Answer 14

Cl2 displaces Br- and I- forms orange and violet
Br2 displaces I- forms violet solution I2 in cyclohexane

Question 15

Halogen reactivity tren

Answer 15

Decreases down the group as atomic radius increases so less nuclear attraction to capture electron from other species

Question 16

Disproportionation

Answer 16

when one species is oxidised and reduced in the same reaction equation
Cl2 and water forms HClO and HCl
Cl2 with NaOH forms NaClO and NaCl

Question 17

Chlorine use

Answer 17

Chlorine kills bacteria in water sources
However is extremely toxic and is a respiratory irritant
Chlorine can react with methane to form chlorinated hydrocarbons which can cause cancer

Question 18

Test for anions

Answer 18

Carbonate test
Sulfate test
Halide test

Question 19

Carbonate test

Answer 19

Add to dilute nitric acid
If bubble carbonate could be present if like water cloudy carbonate was present

Question 20

Sulphate test

Answer 20

Ba2+ ions added as BaCl2 or BaNO3
Barium sulphate is very insoluble in solution
if SO4 present white pp forms

Question 21

Halide tests

Answer 21

Add silver nitrate
Cl- is white Br- is cream I- is yellow
Cl- is soluble in dilute NH3
Br- is soluble in conc NH3
I- is insoluble in conc NH3

Question 22

Sequence of tests

Answer 22

1. Carbonate
2. Sulphate- barium carbonate is also white and insoluble
3. Halides-silver carbonate and sulphate are also insoluble in water and forms pp