Question: how many unpaired electrons does one chlorine atom have?
Answer: The electronic configuration of chlorine is [Ne]3s23px23py23pz1. Thus, it contains 1 unpaired electron. In the first excited state, 1 electron is transferred from 3p to 4s orbital. The electronic configuration becomes [Ne]3s23px23py13pz14s1 Thus, three unpaired electrons are present in the excited state.