Group 2 - Alkali earth metals

Question 1

what is the trend of atomic radius in group 2 from Mg to Ba?

Answer 1

• increases down the group

- each element gains an extra filled main levels of electrons

Question 2

what is the trend of first ionisation energy in group 2 from Mg to Ba?

Answer 2

• decreases down the group

- electrons further away from nucleus so more shielding by inner shells

Question 3

what type of structure of group 2 metals have?

Answer 3

• metallic structure

- lattice of positive ions in a sea of delocalised electrons

Question 4

what is the trend of melting point in group 2 from Mg to Ba?

Answer 4

• decreases down the group

- delocalised electrons further away from nuclei therefore strength of metallic bond decreases

Question 5

which element does not fit trend of decreasing melting point?

Answer 5

magnesium - has a much lower melting point than expected because it has a different lattice structure

Question 6

what is the trend of reactivity in group 2 from Mg to Ba?

Answer 6

increases down group because ionisation energy decrases

Question 7

how do group 2 metals react with water?

Answer 7

form metal hydroxide and hydrogen

Question 8

what is the oxidation state when group 2 reacts with water?

Answer 8

0 to -2

Question 9

how does magnesium react with cold water and steam?

Answer 9

slow with cold water but vigorously with steam

Question 10

what is the trend of solubility of hydroxides of group 2 metals from Mg to Ba?

Answer 10

increases down the group

Question 11

what is the trend of solubility of sulphates of group 2 metals from Mg to Ba?

Answer 11

decreases down the group

Question 12

test for sulphates

Answer 12

• add nitric/ HCl acid to remove any carbonate ions
• add acidified BaCl2 solution
• white precipitate of barium sulphate will be formed if sulphate present

Question 13

use of barium sulphate

Answer 13

• insoluble

- use for x rays - forms a suspensions and outlines digestive system for easier visibility

Question 14

use of magnesium hydroxide

Answer 14

• sparingly soluble

- used in milk of magnesia - aids indigestion/ induce defecation

Question 15

use of calcium hydroxide

Answer 15

• used in agriculture

- neutralise acidic soils

Question 16

use of calcium oxide/carbonate

Answer 16

• remove sulphur dioxide from flue gases

- because it is alkaline it reacts with acidic gas to form solid waste product of calcium sulfite

Question 17

use of magnesium

Answer 17

• used in extraction of titanium
• titanium oxide converted to titanium oxide by heating with carbon in a stream of chlorine gas
• purified by fractional distillation
• magnesium then reduced titanium by donation electrons
• the product of magnesium chloride can be electrolysed and recycled