Question

Position of hydrogen was not justified with alkali metals in the periodic table. Explain.

Answer 1

Position of hydrogen was not justified with alkali metals in the periodic table because of following differences in properties from the alkali metal:
1. H is a non-metal whereas alkali metals are metals.
2. At room temperature, H is a gas whereas alkali metals are solids.
3. H forms both ionic and covalent bond whereas alkali metals form only ionic           bonds.
4. H requires very high energy for ionisation compared to the alkali metals.

Answer 2

Hydrogen was placed in group 1 but it resembled properties of both group 1 alkali metals and group 7 halogens.
Hydrogen has its electronic configuration as 1s^1.
Both group 1 and group 7 elements also have same configuration in there outer most shell.
So there is a great confusion in the position of hydrogen.