(inorganic chemistry) A colourless, very poisonous, volatile liquid, HCN, used in the production of dyes, plastics and fumigants; it dissolves in water to form hydrocyanic acid and reacts with bases to form cyanides, and with some organic compounds to form nitriles.

(inorganic chemistry) A colourless liquid, H₂O₂, soluble in water, used as a mild antiseptic, bleaching agent (especially for bleaching hair), oxidizing agent and chemical reagent.

(chemistry) monatomic hydrogen that exists transiently after the reduction of a hydrogen ion; generated from zinc and hydrochloric acid; it is a strong reducing agent

(chemistry) A weak bond in which a hydrogen atom in one molecule is attracted to an electronegative atom (usually nitrogen or oxygen) in the same or different molecule.

(chemistry) To bond to another species by means of hydrogen bonds. E.g. Water hydrogen bonds with itself.

(chemistry, obsolete) hydrogen selenide

(obsolete, chemistry) hydrogen sulphide

(inorganic chemistry) A toxic gas, H₂S, smelling like rotten eggs and used in analytical chemistry and industry.

(obsolete, chemistry) hydrogen

(chemistry) linked by a hydrogen bond