Question

why helium is Noble gas ? while it doesn't contain p orbital​

Answer 1

Answer:

Noble gas is the gas where the orbital are fulfilled . There is no free electron and no charge .

Helium has 2 electron in K shell .

So it's orbit is valanced .

Answer 2

We know that only valence electrons can take part in a chemical reaction. In Inert gases or Noble gases a set of 8 electrons is in the outermost orbit being very stable which doesn't allow outermost shell to part in chemical reaction.

Although, Helium in group does not has a set of 8e- , it contains only 2e- in the outermost shell. 2e- set in an atom and present in the outermost of the shell also said to be stable only when the outermost shell is first and no other e- is present in atom.

For Helium K shell is the first and last shell so it has only two set of electrons.