How could Cl change to gain stability?

lose 7 electrons
gain one electron

Answer: gain one electron

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:

[tex][Cl]=1s^22s^22p^63s^23p^5[/tex]

Chlorine atom will gain one electron rather than lose 7 electrons to gain noble gas configuration and form chloride ion with -1 charge.

[tex][Cl^-]=1s^22s^22p^63s^23p^6[/tex]