Section outline

  • Molecules are built of permanent numbers of atoms joined together by covalent bonds, and can variety from the very small (even down to single atoms, as in the noble gases) to the very large (as in polymers, proteins or even DNA).

    The covalent bonds keeping the molecules together are very strong, but these are largely immaterial to the physical properties of the substance. Physical properties are ruled by the intermolecular forces - forces attracting one molecule to its neighbours - van der Waals attractions or hydrogen bonds.