Nitrogen due to smaller size, high ionisation energy high electronegativity and the absence of $d$ -orbital does not exist as a tetra atomic molecule
Nitrogen cannot form $d \pi$ - $p \pi$ bond due to absence of $\alpha$ -orbital, so it cannot expand its covalency beyond four as the heavier members of this group can
P block elements are those in which the last electron enters any of the three p-orbitals of their respective shells. Since a p-subshell has three degenerate p-orbitals each of which can accommodate two electrons, therefore in all there are six groups of p-block elements.
P block elements are shiny and usually a good conductor of electricity and heat as they have a tendency to lose an electron. You will find some amazing properties of elements in a P-block element like gallium. It’s a metal that can melt in the palm of your hand. Silicon is also one of the most important metalloids of the p-block group as it is an important component of glass.