Sulfur has six valence electrons, meaning that each atom of this element has six electrons in its outermost shell. The number of valence electrons that each element has can be predicted based on its location on the periodic table, though this only applies to neutral atoms. An element's main group number indicates how many valence electrons each atom of that element will have, and because sulfur is part of group six on the periodic table, this indicates that this element has six electrons in its outermost electron "shell."
Like sulfur, oxygen is an element that has six valence electrons. This can be easily predicted by noticing that oxygen shows up under group six in the periodic table. Other elements that share this characteristic include selenium and tellurium. This rule only applies to neutral, or uncharged, atoms.
When atoms are charged, the number of electrons in its outermost energy level, or shell, will change based on the amount of charge. For example, if sulfur is charged to S-2, this means that sulfur now has eight, or two in addition to its usual six, valence electrons.
Knowing the number of an element's valence electrons can be helpful in knowing how it will bond with other atoms. In some cases, the term "valence electrons" may be abbreviated as VE.