Hydrogen has one electron, helium has two electrons, and lithium has three electrons. Hydrogen and lithium are both reactive, but helium is unreactive. How could the quantum mechanical model of the atom explain this pattern of behavior?
Basically Helium gas is inert and it shows duplet behaviour. It has two electrons in it's valence shell hence the duplet rule is obeyed. He gas does not need any more electrons to get stable because it is already stable
