Anomalous Behaviour of Beryllium:

Beryllium, the first member of the group 2 metals, shows anomalous behavior as compared to magnesium and rest of the members. Further it shows diagonal relationship to aluminum which is discussed subsequently:

(I)                 Beryllium has exceptionally small atomic and ionic sizes and thus does not compare well with other members of the group. Because of high ionization enthalpy and small size it forms compounds which are largely covalent and get easily hydrolysed.

(II)               Beryllium does not exhibit coordination number more than four as in ts valence shell there are only four orbitals. The remaining members of the group can have a coordination number of six by making use of d-orbitals.

(III)             The oxide and hydroxide of beryllium unlike the hydroxides of other elements in the, are amphoteric in nature.