Question

What is the maximum covalency of first elements of each group?

Answer 1

Hint : Covalency can be defined as the maximum number of covalent bonds that an atom can form using its empty orbitals. Also, covalency can be given only for elements that can form covalent bonds. It depends upon the number of valence electrons and the number of empty orbitals present in an atom.

Complete Step By Step Answer:
We have seen what covalency is but we should not fuse it with valency. Valency is the number of electrons that an atom can gain or lose in order to stabilize itself. It gives the number of electrons required to fill the empty orbitals. Valency can be given for elements that can form ionic as well as covalent bonds.
It is a common observation that the first element of each group show anomalous behaviour, which may be due to;
Small size in their respective groups
High electronegativity (due to small size)
Non-availability of d-orbital
It has been found that the maximum covalency of first elements of each group is 4.
We can see for Group-14 (carbon family)
First element is carbon having electronic configuration;
$C = 1{s^2}2{s^2}2{p^2}$
It has four valence electrons which it can share to form four covalent bonds. It can show a maximum covalency of four.
We can also look for Group-15 where Nitrogen also shows maximum covalency of four.
Thus, the maximum covalency of first elements of each group is four.

Note :
It should be noted that from the third period and onwards cavalency may be variable because of the presence of d-orbital. Covalency is generally positive or zero (in noble gases) but oxidation state can be negative, positive, fraction.