Oxidation Numbers in Ions
Part of the Oxidation and Reduction section of Coddy's Chemistry journey. Lesson 4 of 27.
In an ion, the numbers add up to the ion's charge. SO₄²⁻: S + 4(−2) = −2, so S is +6.
NH₄⁺: N + 4(+1) = +1, so N is −3.
One element can take many numbers: nitrogen is −3, +2, +4 and +5 in NH₄⁺, NO, NO₂ and NO₃⁻.
Challenge
The dichromate ion, Cr₂O₇²⁻, gives orange solutions and was once used in breath tests for alcohol. Give each element its oxidation number.
Try it yourself
Oxidation numbersGive the oxidation numbers in Cr2O72−
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