“Hydrogen occupies a unique position

The position of the element hydrogen is still not clear even in the Modern Periodic Table.

• In electronic configuration, it resembles alkali metals of group 1. All of them have only one electron in the valence shell. Actually, hydrogen has

only one shell (K-shell) which has one electron. However, it is not a metal whereas alkali-metals are metallic in nature.

• In characteristics, it resembles halogens of group 17. For example, like halogens hydrogen is a non-metal and diatomic as well.

It has been therefore, decided to assign hydrogen a unique position in the Modern or Long Form. Periodic Table. It is placed at the top in group 1

of alkali metals. However, it is not a member of that group.*