The Chemical Bond: Lewis and Kossel’s Landmark Contribution

The seminal papers of Lewis and Kossel in 1916 are put into a historical perspective. Mendeleev’s periodic table, Thompson’s discovery of the electron, Ramsay and Raleigh’s discovery of the noble gases, Rutherford’s model of the atom and Bohr’s description of the stationary orbitals for the electrons in atoms all paid an important role in providing the background for Lewis and Kossel’s proposal that the chemical bond originated either from the transfer of electrons or the sharing of electron pairs. These insights depended on the attainment of inert gas configurations by the atoms either directly by electron transfer or electron-pair sharing. The model incorporated an evolutionary gene which has enabled it to survive and grow by incorporating subsequent developments in quantum physics. The simplicity of the model has resulted in the development of a notation, which is universally used by chemists and has evolved to plot the course of chemical reactions and predict their regioselectivities. Its initial limitations are discussed, and the way in which they have been overcome by an orbitally based model is recounted. The model has been repeatedly enriched by quantum mechanically based theoretical studies.