Question: what is the electronic configuration and valency of chlorine?
Answer: The electronic configuration of chlorine can be written as 2, 8, 7. 2, 8, 7 electrons are distributed in the shells K, L, M respectively. Therefore, valence electron in chlorine is 7 and it needs to gain 1 electron from the outermost orbit to attain octet. Hence, the valency of chlorine is 1.