A molecule is a particle in which two or more atoms are strongly bonded together and which behaves as a single unit in physical and chemical processes. Molecules are the basic units of molecular substances, just as ions are the units of ionic substances. A water molecule, for instance, consists of two hydrogen atoms bonded to one oxygen atom.

分子是两个或多个原子牢固结合在一起、在物理和化学过程中作为独立单元的粒子。分子是分子物质的基本单元,正如离子是离子化合物的单元一样。例如,一个水分子由两个氢原子与一个氧原子结合而成。