Boron exhibits anomalous behaviour in the company of other members of group 13. Explain.

Boron differs from other elements of group 13 due to its:
(i) small size
(ii) high electronegativity and high ionisation energy
(iii) non-availability of d-orbitals.

Main points of difference:
(i) Boron is non-metal while other members of the group are metals.
(ii) Boron is a bad conductor of electricity while other members are good conductors of electricity.
(iii) The melting and boiling points of boron are much higher than those of other members of the group.
(iv) Boron exhibits maximum covalency of four as in [BH₄]^– ion while other members exhibit a covalency of six as in [Al (OH)₆]^3–.
(v) Boron forms a large number of hydrides called boranes while other members do not do so.
(vi) B(OH)₃ i.e. H₃BO₃ is acidic while Al(OH)₃ as well as Ga(OH)₃ is amphoteric; indium and thallium hydroxides are basic.