Molecule

Name:
Molecule
Detailed information:
A chemical unit composed of one or more atoms. The simplest molecules contain only one atom, for example, helium molecules (1 atom/molecule). Oxygen molecules (O₂) are composed of two atoms, and ozone (O₃) of three. Molecules may contain several different sorts of atoms. Water contains two different kinds, hydrogen and oxygen, and dimethylamine [(CH₃)₂NH] has three kinds. Molecules of many common gases [hydrogen (H₂), oxygen (O₂), nitrogen (N₂), and chlorine (Cl₂)] consist of two atoms each. The atoms of a molecule are held together by chemical bonds. Molecules vary in size from less than 1 to more than 500 millimicrons and in weight from 4 (He) to 40 million for tobacco mosaic virus.See Macromolecule; Bond, Chemical; Atom.