What happens when a chlorine atom gains an electron in its outer energy shell?

It becomes an ion, which has a charge. And the charge would be negative.

Heyhonestly, probably not. humans have always had a tendency to waste things. whether it's food, cosmetic, infrastructure, or our abandoned constructions,the landscape is littered with the refuseof man. archaeology wouldn't be a developed discipline if humans didn't leave things behind. in a way it makes us human

hope it mark me as brainlieast.