The chemical formula for laughing gas is N₂O.
Laughing gas is the common name for nitrous oxide, a colourless, non-flammable gas made of two nitrogen atoms bonded with one oxygen atom. Its systematic names include dinitrogen monoxide and dinitrogen oxide. The formula distinguishes it from nitrogen dioxide (NO₂), nitric oxide (NO), and dinitrogen tetroxide (N₂O₄), all different nitrogen oxides.
English chemist Joseph Priestley first synthesised nitrous oxide in 1772. Humphry Davy studied its effects in the 1790s and coined the name “laughing gas” after observing euphoria and laughter during inhalation. In medicine, it is used for pain relief and sedation, especially in dentistry and childbirth, often mixed with oxygen.
The gas also has non-medical uses: it propels whipped cream from aerosol canisters and serves as an oxidiser in some racing engines and rocket systems. Despite its familiar nickname, misuse can cause oxygen deprivation and vitamin B₁₂-related neurological injury.