Answer: gain one electron
Step-by-step explanation:
Chlorine is an element with atomic number 17 and thus contain 17 electrons. It is a p block element as the last electron enters the p orbital.
The electrons are filled according to Afbau's rule in order of increasing energies and thus the electronic configuration of chlorine is:
Chlorine atom will gain one electron rather than lose 7 electrons to gain noble gas configuration and form chloride ion with -1 charge.
![[Cl^-]=1s^22s^22p^63s^23p^6](https://img.qammunity.org/2019/formulas/chemistry/middle-school/ydx4j9w99w3f93kz0r9yam5lkrs8t18rb8.png)