Hydrogen Cyanide : Linear Molecular Geometry

   In this example, HCN, the Lewis diagram shows carbon at the center with no lone electron pairs. The carbon and nitrogen are bonded through a triple bond which counts as one electron pair. Hence the molecule has two electron pairs and is linear. Hydrogen cyanide is prepared on an industrial scale by the reaction of methane with ammonia in the presence of a platinum catalyst at 1200^o C. It boils at 25^oC, and thus is a gas a room temperature. HCN is very toxic and will cause death in a matter of minutes if inhaled or ingested.