Question

When a nonmetal atom gains (an) electron(s), what does it become?

Answer 1

an anion

Explanation:

When an atom gains an electron, it has more electrons (negative) than protons (positive). This means that it has an overall negative charge, and is called an anion (not to be confused with onion).

For example, Chlorine `(Cl)` gains an electron to become `Cl^-` as it has gone from having 17 electrons as chlorine, 7 of which are valence electrons, and 17 protons - equal numbers so overall charge is zero - to having 18 electrons as the chloride ion - 8 valence electrons. 18 negative electrons compared with 17 positive protons means the ion is negatively charged.