$B_{2} H_{6}$ is electron deficient molecule because boron atom has three half-filled orbitals in excited state. The structure of $B_{2} H_{6}$ is represented as follows:
In it two electrons of a $B-H $ bond are involved in formation of three centre bond, these bonds are represented as dotted lines.
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.
