Question

Write short notes on the Anomalous behaviour of Boron in the group 13

Answer 1

In each group first element has anomalous behaviour.

It is due to :-

(a) it has comparatively high electronegative value

(b) it's very small in size as compared to other elements in the same group

(c) non availability of d- orbitals in the valence shell for the formation of Bond

Boron, the first element of group 13 elements differ from the rest of the elements in the following properties

Anomalous properties of Boron :-

i)Boron is non metallic while the rest of the elements have metallic nature

ii)Boron exhibits allotropy. Aluminium and other members do not show any allotropy

iii)The compounds of Boron are covalent the compounds of aluminium are covalent in anhydrous state but are ionic in Aqueous solutions the compounds of the other members are ionic in nature

iv)Boron exhibits +3 Oxidation State in its compounds other metals have tendency +1 to show as well as +3 oxidation states in their compounds

v) Boron can show maximum covalency of four due to absence

of d - orbital aluminium and other elements can show

covalency of 4 as well as 6 due to large size and availability of

vacant d - orbital

Answer 2

Anomalous properties of Boron :-

i)Boron is non metallic while the rest of the elements have metallic nature

ii)Boron exhibits allotropy. Aluminium and other members do not show any allotropy

iii)The compounds of Boron are covalent the compounds of aluminium are covalent in anhydrous state but are ionic in Aqueous solutions the compounds of the other members are ionic in nature

iv)Boron exhibits +3 Oxidation State in its compounds other metals have tendency +1 to show as well as +3 oxidation states in their compounds

v) Boron can show maximum covalency of four due to absence of d - orbital aluminium and other elements can show covalency of 4 as well as 6 due to large size and availability of vacant d - orbital