Question

Why helium is considered as p orbital instead of s orbital?

Answer 1

Helium is having electronic configuration 1s² that is a configuration of s block element then it should be kept in s block. But it is not placed because of its properties only those match with inert gases.

*Helium is gas like other inert gases unlike solid s block metals.
*Helium is non- metal while s block contains only metals.
*Helium is much less reactive like other inert gases unlike s block metals which are most reactive.
*Helium also possess a completely filled electronic configuration like other inert gases.

For all such reasons Helium is placed in inert gases group which lies in p block.