Nitrogen and sulfur

Learning objectives

Explain why N₂ is so unreactive, referring to the very high bond energy of N≡N and the absence of a bond dipole

Describe ammonia as a Brønsted–Lowry base, the formation and shape of the ammonium ion, and the release of ammonia when an ammonium salt is warmed with a base

Describe how nitrogen oxides form naturally (lightning) and in vehicle engines, and how a catalytic converter removes them from exhaust gases

Explain how NO and NO₂ contribute to photochemical smog by forming peroxyacetyl nitrate (PAN) with unburnt hydrocarbons, and to acid rain, including their catalytic role in oxidising SO₂ to SO₃