What is the oxidation number?
The number of electrons that an atom uses to bond with atoms of another element.
What is the oxidation number of an uncombined element?
0
What is the oxidation number of combined oxygen?
-2
What is the oxidation number of combined oxygen in peroxides?
-1
What is the oxidation number of combined hydrogen?
+1
What is the oxidation number of combined hydrogen in metal hydrides?
-1
What is the oxidation number of a simple ion?
Charge on ion.