Question

how come some elements have both positive and negative oxidation numbers and what determines whether they'll be either positive or negative??????

Answer 1

Explanation:

An element in a free form has OS = 0. In a compound or ion, the sum of the oxidation states equals the total charge of the compound or ion. Fluorine in compounds has OS = −1; this extends to chlorine and bromine only when not bonded to a lighter halogen, oxygen or nitrogen