Coupon Accepted Successfully!


Anomalous Behaviour of Beryllium

Beryllium, the first member of Group 2, differs from the other members of its group. This is primarily due to its small size, relatively high electro-negativity and availability of only four orbitals (one 2s and three 2p) in the valence shell. A few points of differences are as follows.
  1. Beryllium forms bonds with appreciable covalent character.
  2. Beryllium salts hydrolyze in aqueous solution producing H3O+. This is due to the formation of a stronger Be—O bond.
  3. Beryllium forms large number of complexes with coordination number four. The tendency for other metals to form complexes is comparatively low.
  4. Be(OH)2 is amphoteric while the hydroxide of other metals are basic.

Diagonal Relationship of Beryllium with Aluminium

Beryllium shows resemblances to diagonally placed Aluminium due to similar values of charge/radius ratio and electro negativity. A few points regarding resemblences are as follows.
  1. Both beryllium and aluminium become passive by concentrated nitric acid due to the formation of an inert layer of the oxide on the surface.
  2. Both beryllium and aluminium react with alkali to form beryllate, [Be(OH)4]2- and aluminate, [Al(OH)6]3-.
  3. Both Be(OH)2 and Al(OH)3 are amphoteric.
  4. Both beryllium and aluminium form polymeric halides.
  5. Both the metals form nitrides which liberate ammonia when treated with water.
    Be3N2 + 6H2O 3Be(OH)2 + 2NH3
    AlN + 3H2O Al(OH)3 + NH3.
  6. Carbides of both elements give methane on hydrolysis.
    Be2C + 4H2O 2Be(OH)2 + CH4
    Al4C3 + 12H2O  4Al(OH)3 + 3CH4.
  7. Both Be2+ and Al3+ form complexes like [BeF4]2-, [Be(C2O4)2]2-,
    [AlF6]3- and [Al(C2O4)3]3-.

Test Your Skills Now!
Take a Quiz now
Reviewer Name