Atomic Radius:
Increases down group 2 as electrons are added to energy shells further away from the positive nucleus.
Ionisation Energy:
Decreases down group 2, as although nuclear charge increases, electron shielding & atomic radius
increase, so less electrostatic attraction of outer most electron to positive nucleus, giving a lower ionisation
energy.
Melting Point:
Decreases down group 2 as the ionic radius increases but same number of electrons donated to the cloud,
so gives a lower electron cloud density, meaning there is less electrostatic attraction between the positive
metal ions and the negative electrons, giving a lower MP.
Group 2 metals react very violently with both cold water and steam to produce hydroxides. With steam,
the reaction is much faster and more violent.
Sulfates:
The sulfates are of group 2 metals. The solubility decreases down the group, with BaSO4 being completely
insoluble (used in Barium Meals) and MgSO4 being very soluble.
Test for Sulfates;
Add HCl to the solution to remove carbonate ions, preventing a negative result. Add BaCl2 to the solution of
suspected sulfate. If sulfate is present, a white precipitate of barium sulfate (insoluble) will be formed.
Watch out for this in reverse, i.e. if BaCl2 is present, you add a sulfate (H2SO4) to the solution, forming a white
precipitate.
