Group 2

Increases down the group

Because:

• More electrons in atoms going down the group
• More layers = electrons repel

Decreases down the group

Because:

• More shielding = attraction from nucleus cancelled out
• Increase in atomic radius = outer electron further from nucleus

Decreases down the group -EXCEPT Mg

Metallic bonding

Because:

• Ionic radius increase = sea of delocalised electrons further away from nucleus = less atrraction
• Mg anomly due to its crystaline strucuture

Increases in reactivity down the group

Cold water:

X(s) = 2H2O(l) --> X(OH)2(aq) = H2(g) 

Steam:

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

Usually:

In earth as oxide / extracted with carbon = metal oxide + carbon --> metal + carbon dioxide

Can't be used with titanium as metal reacts with carbon to form titanium carbide = metal brittle

So:

• Reacted with chlorine/carbon = TiCL4 and CO
• Titanium then reduced by Mg
• TiCl4 + 2Mg --> 2MgCl2 + Ti

Increase in solubility down the group.

• Mg(OH)2 - suspension
• Ca(OH)2 - sparingly soluble - lime water
• Sr(OH)2 - soluble
• Ba(OH)2 - dissolves = strong alkaline solution

Beacause energy needed to form X+ decreased due to decrease in ionisation enery.

Mg(OH)2 - milk of magnesia

Ca(OH)2 - slakes lime - treats acidic soil in agriculture.

Decreases down the group.

BaSO4 - insoluble = barium meal, X-ray digestive system (toxic = no problem not absorbed)

Test for sulphate ions:

• solution acidified (removes carbonate ions - barium carbonate = white presipitate false result)
• barium chloride added - sulphate present = BaSO4 formed - white presipitate.

Flue gas produced from burning fossil fuels.

CaO(s) + 2H2O(l) + SO2(g) + 1/2O2 --> CaSO4.H20(s)

Atomic Radius - Increases

Reactions with Water -Increases

Solubility of Hydroxides in Water - Increases

First Ionisation Energy - Decreases

Melting Point - Decreases

Solubility of Sulphates in Water - Decreases