Atoms can combine with other atoms to form molecules, which are groups of two or more atoms attached together. that act as a single unit. When two atoms form a molecule, the individual atoms interact through what is called a chemical bond, a form of attraction between atoms that holds them together. The ability of atoms to form bonds with other atoms explains in part why just a few types of element can come together in many different ways to make a variety of molecules that can carry out diverse functions in a cell. There are several ways in which atoms can interact with one another, and therefore many different types of chemical bond.