Odium ions have a charge of what?

oxidation number

An ion does have a charge. That is what makes it an ion.

either negative or positive charge always

You have to see how many protons are there and how many electrons are there. If there are more electrons than protons, then the ion has a negative charge. If there are more protons than electrons,...

It depends on the element, ions have different charges based on the number of electrons in the elements outer shell. It can also be positive or negative based on whether it gains or loses electrons,...