What are the valences of chlorine, oxygen, nitrogen, and carbon?
Answer The concept of valence is useful because it allows us to guess at the formulas for compounds two elements will form. For example, a compound between oxygen and fluorine would be expected to have the formula F2O, because fluorine has a valence of one, and oxygen has a valence of two. However, there is a problem. Many elements have several possible valences. Sulfur, for example, usually has a valence of 2 (as in H2S). But in some compounds, it has a valence of four (as in the highly reactive compound SF4) or even six (as in SF6, which is one of the most inert chemical compounds known). So the formulas of compounds guessed using the most common valences of elements are not always correct.
