* Sulfur's electron configuration: Sulfur has 16 electrons, with the following configuration: 2, 8, 6. This means it has 6 electrons in its outermost shell (valence electrons).

* Octet rule: Atoms tend to gain, lose, or share electrons to achieve a stable configuration of 8 electrons in their outermost shell (the octet rule).

* Sulfur's stability: To achieve a stable octet, sulfur needs to gain two more electrons. This gives it a total of 8 electrons in its outermost shell, making it isoelectronic (having the same electron configuration) with the noble gas Argon (Ar).

Therefore, sulfur gains two electrons to achieve stability.