Question

Why are nometals bad conducters of electricity?

Answer 1

Non-metals are electron gainers,i.e. they tend to gain electrons in their valence shell electrons….while metals are electron givers or looser for a similar reason.

So metals have contain free electrons in their outermost shell while non-metals don't and these electrons are ones which cause the electric current by their coordinated movement.

Thats why, most non-metals are poor conductors of electricity(i.e. due to a deficiency of free electrons).

Graphite(carbon) is an exception in this case but thats a different topic and more related to chemistry than physics.