Periodicity

Question 1

Group 2 reaction both oxygen

Answer 1

Metal oxide forms

Question 2

Group 2 reaction with water

Answer 2

Alkaline hydroxide & hydrogen forms

Reaction becomes
more vigorous down group
∵reactivity increases

Question 3

Group 2 general reactivity

Answer 3

Loses 2 outer shell electrons

Reducing agent

Question 4

Group 2 reactivity trend

Answer 4

Down group
atomic radius increases
shielding increases
∴nuclear attraction on
highest energy electron
decreases
so electron easier to lose

Question 5

Group 2 reaction with dilute acid

Answer 5

Salt & hydrogen form

Question 6

Reaction of group 2 oxides with water

Answer 6

Alkaline solution
of hydroxide ions formed

eg. CaO + H2O -> Ca(OH)2

Solubility increases down group
so solutions become more alkaline
(pH increases)

Question 7

Uses of group 2 compounds

Answer 7

Medicine: indigestion remedies

Agriculture: neutralisation of acidic soil

Question 8

Successive ionisation energy

Answer 8

Removing each electron
in an atom in turn
from outer to inner electrons

Question 9

General trend of ionisation energy

Answer 9

Increases
with each ionisation
ionic radius decrease
nuclear attraction increase
more energy needed
to remove each electron

Question 10

Chlorine colours (Cl2)

Answer 10

Room temp: pale green gas
Aq solution: pale green
Organic solvent: pale green
Vapour: pale green

Question 11

Bromine colours (Br2)

Answer 11

Room temp: orange/brown liquid
Aq solution: Orange
Organic solvent: Orange
Vapour: Orange

Question 12

Iodine colours (I2)

Answer 12

Room temp: grey/black solid
Aq solution: Brown
Organic solvent: violet
Vapour: purple

Question 13

Reactivity trend of group 7

Answer 13

Down the group
atomic radius increases
shielding increases
∴nuclear attraction
to capture electrons
from other species
decreases

Reactivity & oxidising strength decreases

Question 14

Halogen-halide displacement reactions

Answer 14

Test tube reaction
to show trend in reactivity

If halogen more reactive than halide
reaction occurs

Chlorine displaces bromide & iodide
Bromine displaces iodide
Iodine displaces nothing

Cyclohexane (non-polar solvent)
often added
so halogens dissolve
better than in water
so more distinctive colours

Question 15

Halides in ammonia

Answer 15

Chloride:
White ppt dissolves in
dilute & conc NH3

Bromide:
Cream ppt dissolves in
conc NH3

Iodide:
Yellow ppt
does not dissolve

Question 16

Reactions of chlorine

Answer 16

Added to drinking water
to kill bacteria
Cl2 + H2O -> HClO + HCl

Bleach made from
reacting cold dilute NaOH with Cl2
Cl2 + NaOH -> NaCl + NaClO +H2O