3.2.2 - group 2 the alkaline earth metals

Atomic radius increases as you go down the group

Increased number of e- Increased number of shells

Decreases down group 2

Increased number of shells Increased dist from nucleus Nucleus cannot attract electrons in a covalent bond so easily

Melting points decrease down group 2

As you go down the group Metal becomes bigger so e- further away from positive ions and thus have less electrostatic attraction so less energy needed to overcome bonds

First ionisation energy decreases down the group

Each element down group 2 has an extra electron shell compared to the one above The extra inner shells shield the outer e- from attraction of the nucleus Extra shell outer e- further from nucleus, weaker attraction so e- can be removed more easier

As you go down the group reactivity increases

As you go down the group first ionisation energy decreases This is due to increasing atomic radius and shielding effect When group 2 metals react they loose e-., the easier to loose e- (lower the first nd second ionisation energy) the more reactive the element so reactivity increases down the group

Metal hydroxide + hydrogen

Oxidising agent

Hydroxides increase in solubility down the group

Sulphates decrease in solubility down the group

Barium sulfate (BaSO4)

White precipitate

Used to test for sulphate ions

Add acidified barium chloride (Bacl2) A white ppt of barium sulfate will form (+ve test result)

To remove ions that will also produce white ppt giving false positive

Barium meals to absorb x rays. It’s insoluble and not absorbed by the body so it’s harmless.

Stored in oil to keep out of contact with air

Solid metal oxides that are white in colour

Magnesium hydroxide and hydrogen gas Mg (s) + 2 H2O (l) → Mg (OH)2 (aq) + H2 (g)

Hot magnesium reacts with steam vigorously producing a ( bright light, white powder these are the observations ) and forming magnesium oxide and hydrogen gas. Mg (s) + H2O (g) → MgO (s) + H2 (g)