Question

Can nonmetals have both positive and negative oxidation numbers?

Answer 1

Yes non metals can have both positive and negative oxidation numbers.

Explanation:

If a non metal combines with a metal, metalloid or non metal with a lower electro negativity than the non metal the non metal will have a negative charge or oxidation number.

An example is Sulfur combining with Hydrogen. Sulfur has a higher electro negativity than Hydrogen and will draw more of the electrons to the Sulfur's side of the chemical bond causing Sulfur to be `S^-2` The Hydrogen will become `H^+1` so the formula will be
`H_2^+1S^-2`

If a non metal combines with a non metal with a higher electro negativity than the no n metal then the non metal with have a positive charge.

An example is when sulfur combines with Oxygen. Oxygen has a higher electro negativity that then Sulfur, so Sulfur will " lose" electrons to Oxygen. that is the electrons will be pulled closer to the Oxygen causing Oxygen to have a negative charge and the Sulfur to have a positive charge.

`H_2SO_4` The sulfur has a charge of +6 as all six of its valance electrons are pulled closer to the 4 Oxygen atoms than the Sulfur atom. The two Hydrogen atoms also "lose" their electrons to the Oxygen creating a total positive charge of +8 to balance the negative charge of the -8 on the four Oxygens.

Note Florine having the highest electro negativity is never positive.