Trends in Group 2 Compounds

Group 2 Elements are called Alkali Earth Metals.

They are called s-block elements because their highest energy electrons appear in the s subshell.

Progressing down group 2, the atomic radius increases due to the extra shell of electrons for each element.

Going down the group, the first ionisation energy decreases. There is more shielding between the nucleus and the outer electrons and the distance between the nucleus and the outer electron increases and therefore the force of attraction between the nucleus and outer most electrons is reduced.

Generally the melting point of the metals decreases down the group. This is because as the metal ions get larger the distance between the bonding electrons and the positive nucleus gets larger and reduces the overall attraction between the two. For similar reasons the electronegativity decreases.

The reactions of the elements with water become more vigorous down the group.

When they do react they produce hydroxides and hydrogen.

The solubilities of the hydroxides of the elements increase going down the group.

The solubilities of the sulphates of the elements decreases down the group.

A hint:  BaSH MgSS   (say it as BASH MAGS)

Barium has a soluble hydroxide, Magnesium has a soluble sulphate.

Barium sulphate is insoluble and is used as a qualitative test to identify sulphate ions.

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