Oxidation Numbers
Part of the Oxidation and Reduction section of Coddy's Chemistry journey. Lesson 2 of 27.
An oxidation number is the charge an atom would have if every bond were ionic. It keeps count of electrons even where they are shared.
An element on its own is 0. A single-atom ion is its charge. In a compound the numbers add up to 0.
With O at −2 and H at +1: in SO₂ the oxygens give −4, so S is +4. A number that goes up means oxidation; one that goes down means reduction.
Challenge
Sulfur dioxide, SO₂, is the gas that comes from burning coal that contains sulfur. Give each element its oxidation number.
Try it yourself
Oxidation numbersGive the oxidation numbers in SO2
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
All lessons in Oxidation and Reduction
1Electron Transfer
What Is OxidationOxidation NumbersRules for Oxidation NumbersOxidation Numbers in IonsRecap - Number Painter