1800 Alessandro Volta lists metals in decreasing order of electropositivity.
1852 British chemist Edward Frankland states that atoms have definite combining power, which determines the formulae of compounds.
1858 August Kekulé shows that carbon has a valency of four—it forms four bonds with other atoms.
1916 American physical chemist Gilbert Lewis shows that a covalent bond is a pair of electrons shared by two atoms in a molecule.
1938 British mathematician Charles Coulson calculates an accurate molecular orbital wave function for hydrogen.
In the late 1920s and early 1930s, in a series of landmark papers, American ...