Answer:
gaining two electrons
Explanation:
A neutral sulfur atom contains 16 electrons. We can know this because its atomic number is 16, which means there are 16 protons in the nucleus. Since the negative charge of the electrons cancels the charge of the protons, the sulfur atom is neutral. The electron configuration of sulfur is 1s22s22p63s23p4. The valence shell (the 3s and 3p sublevels) contains six electrons, but it needs eight to become stable. Think of the octet rule. Therefore a sulfur atom will gain two electrons to form the sulfide anion with a charge of 2−, with the symbol S2−.
