2.2 Group 2 Metals

trend in reactivity down group 2

increases down the group due to increased electron shielding and larger atomic radii so outer electron is easier to lose

reaction of group 2 with water

react with water in a redox reaction, producing a metal hydroxide and hydrogen

• Mg + 2H₂O —> Mg(OH)₂ + H₂

  • magnesium is oxidised

solubility of group 2 hydroxides

increases down the group

• Mg(OH)₂ - sparingly soluble

• Ca(OH)₂ - slightly soluble

• Sr(OH)₂ and Ba(OH)₂ - soluble

solubility of group 2 sulfates

decreases down the group

• barium sulfate is insoluble

uses of magnesium hydroxide

antacid in medicine as its alkaline

uses of calcium hydroxide

slaked lime is used to treat acidic soil for optimal growth

uses of calcium oxide

used in flue gas desulfurisation to prevent pollutants in the atmosphere

• CaO + SO₂ —> CaSO₃

uses of calcium carbonate

limestone

uses of barium sulfate

barium meals in medicine -a medical tracer as barium absorbs x-rays and is insoluble so doesn’t enter the bloodstream

uses of barium chloride

test for sulfate ions - acidified first to remove carbonate impurities

• Ba²⁺ + SO₄^2- —> BaSO₄ (white precipitate)

uses of magnesium

used to extract titanium

• TiO₂ + 2C + 2Cl₂ —> TiCl₄ + 2CO

• TiCl₂ + 2Mg —> Ti + 2MgCl₂