Chemistry

Chemistry

Problem

Deduce the oxidation number of the following atoms and complete the table. The first row has been completed for you.
SubstanceOxidation states
KBrK: +1Br: -1
PCl 5P:Cl:
Fe 2 O 3Fe:O:
NaNO 2Na:N:O:
K2CrO4\text{K}_2\text{CrO}_4K:Cr:O:
H2\text{H}_2H:
SO42−\text{SO}_4^{2-}S:O:
HCO3−\text{HCO}_3^-H:C:O:
NO3−\text{NO}_3^-N:O:
Intuitive explanation

Oxidation numbers follow predictable rules: alkali metals are always +1, oxygen is usually −2 (except in peroxides), and all oxidation states in a neutral compound must sum to zero—or to the charge if it's an ion. Use these rules systematically, assigning known oxidation states first, then solving for the unknown atom by balancing the total.

Intuitive explanation

Oxidation numbers follow predictable rules: alkali metals are always +1, oxygen is usually −2 (except in peroxides), and all oxidation states in a neutral compound must sum to zero—or to the charge if it's an ion. Use these rules systematically, assigning known oxidation states first, then solving for the unknown atom by balancing the total.

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