Group 2 chemistry

Question 1

What is the charge for group 2 ions and why do they have this charge

Answer 1

2+ as they have 2 outer shell electrons which are lost as the ion is formed, this gives a stable 8 outer shell electrons

Question 2

what is the formula of Magnesium with Chloride ions (Cl-)

Answer 2

MgCl2

Question 3

What is the formula of Magnesium with bromide ions (group 17)

Answer 3

MgBr2

Question 4

What is the formula of Magnesium hydroxide (OH-)

Answer 4

Mg(OH)2

Question 5

What happens to group 2 hydroxides solubility as you travel down the group

Answer 5

The solubility increases as you go down the group e.g. Barium Hydroxide is more soluble than Calcium Hydroxide

Question 6

What happens to group 2 carbonates solubility as you travel down the group

Answer 6

They get less soluble as you travel down the group e.g. Calcium Carbonate is less soluble than Magnesium Carbonate

Question 7

What is produced when a group 2 metal reacts with water e.g. Calcium

Answer 7

Calcium hydroxide + hydrogen

Question 8

What is the trend in the reactivity in group 2 metals, and why does this trend happen

Answer 8

-Further down the group = more reactive
- Going down the group there are more occupied shells of electrons. This means the highest energy electrons (outer shell) are further away from the nucleus, which means less energy is required for it to lose the electrons.

Question 9

What are the 4 Metal compounds that tend to be bases

Answer 9

Hydroxides, Oxides, Carbonates and Hydrogen Carbonates

Question 10

Define thermal decomposition

Answer 10

Compounds splitting up due to heat (heat provides energy to break bonds) (different to a combustion reaction as no oxygen is involved)

Question 11

what do group 2 carbonates thermally decompose to e.g. Beryllium carbonate

Answer 11

Beryllium Oxide + Carbon dioxide
(Any oxide + carbon dioxide is formed)

Question 12

What is the trend in thermal stability of group 2 carbonates

Answer 12

Down the group, the carbonates become more thermally stable which means they have to be heated to a higher temperature to decompose.

Question 13

Explain how thermal decomposition affects group 2 carbonate ions as you go down the group

Answer 13

-Carbonate ion has covalent bonds
-Heat can break a bond in the carbonate ion leaving an oxide ion and a carbon dioxide
-The presence of a positive metal ion can distort / polarise the carbonate ion, weakening them meaning less energy is required to break them.
-As you go down the group in group 2, metal ions have a lower charge density meaning they have a weaker positive attraction to the carbonate ion, which means the carbonate ion is less distorted.