The oxidation number of an
uncombined element is
0
The sum of the oxidation numbers in a compound is
0
In an ion, the sum equals
The overall charge
The oxidation number of oxygen is
-2
Except with fluorine or in peroxides
The oxidation number of hydrogen is
+1
Except in metal hydrides
What does an ionic equation focus on
The changes taking place
What is a spectator ion
Any ions that do not change during a reaction
Left out of ionic equations