Here's why:

* Electronic Configuration: Sulfur's electronic configuration is 1s² 2s² 2p⁶ 3s² 3p⁴.

* Valence Electrons: Valence electrons are the electrons in the outermost shell of an atom. In sulfur's case, the outermost shell is the 3rd shell, which contains 6 electrons (2 in the 3s subshell and 4 in the 3p subshell).