Chlorine has seven valence electrons. This is because it is located in Group 17 of the periodic table, which is known as the halogens. Elements in this group typically have seven electrons in their outermost shell.
As for its valency, chlorine typically has a valency of 1. This means that it can gain one electron to achieve a stable electron configuration, similar to that of noble gases, which have full outer electron shells. When chlorine gains an electron, it becomes a negatively charged ion, known as a chloride ion (Cl–).