Oxidation Numbers
What is the oxidation number?
Common Questions
What are oxidation numbers?
Oxidation numbers (oxidation states) are assigned charges that represent the number of electrons an atom has gained, lost, or shared unequally in a compound. They help track electron transfer in redox reactions.
What are the rules for assigning oxidation numbers?
Key rules: free elements are 0, monatomic ions equal their charge, oxygen is usually -2 (except in peroxides: -1), hydrogen is usually +1 (except in metal hydrides: -1), fluorine is always -1, and the sum of all oxidation numbers equals the overall charge.
How do you find the oxidation number of an element in a compound?
Assign known oxidation numbers first (O = -2, H = +1, halogens, etc.). Set up an equation where all oxidation numbers sum to the total charge of the species. Solve for the unknown element.
What is the difference between oxidation and reduction?
Oxidation is an increase in oxidation number (loss of electrons). Reduction is a decrease in oxidation number (gain of electrons). Remember: OIL RIG — Oxidation Is Loss, Reduction Is Gain.