What is the oxidation number of hydrogen when bonded to nonmetals?

What is the oxidation number of hydrogen when bonded to nonmetals?

• A. -1
• B. +2
• C. 0
• D. +1

Answer: (D)

When hydrogen bonds to nonmetals, its oxidation number is +1. The nonmetal is more electronegative and pulls electron density toward itself, so in the oxidation-state counting hydrogen ends up with a positive charge. This shows up in many common compounds: in water, hydrogen is +1 while oxygen is -2; in ammonia, hydrogen is +1 with nitrogen at -3; in methane, hydrogen is +1 and carbon is -4. The sum of oxidation numbers in a neutral molecule is zero, which fits these assignments. The other possibilities don’t match this pattern: -1 occurs in metal hydrides where hydrogen effectively gains electrons from the metal, 0 would be for the elemental H2 molecule, and +2 doesn’t occur for hydrogen in typical compounds.

When hydrogen bonds to nonmetals, its oxidation number is +1. The nonmetal is more electronegative and pulls electron density toward itself, so in the oxidation-state counting hydrogen ends up with a positive charge. This shows up in many common compounds: in water, hydrogen is +1 while oxygen is -2; in ammonia, hydrogen is +1 with nitrogen at -3; in methane, hydrogen is +1 and carbon is -4. The sum of oxidation numbers in a neutral molecule is zero, which fits these assignments. The other possibilities don’t match this pattern: -1 occurs in metal hydrides where hydrogen effectively gains electrons from the metal, 0 would be for the elemental H2 molecule, and +2 doesn’t occur for hydrogen in typical compounds.