Electron-Pair Bond Theory

The electron-pair bond theory holds that a covalent chemical bond forms when two atoms share a pair of electrons between them, each atom typically contributing one electron to the shared pair. Gilbert N. Lewis proposed it in his 1916 paper "The Atom and the Molecule," together with a way of drawing it, now called Lewis structures or Lewis dot diagrams, in which dots around an atomic symbol represent its valence electrons and a shared pair is drawn between bonded atoms. The theory explained why atoms combine in the fixed small-number ratios Dalton's atomic theory had described without explaining, continuing the refinement chain Ernest Rutherford's 1911 discovery of atomic structure began on that entity. Linus Pauling, in The Nature of the Chemical Bond (1939), extended Lewis's picture with the new quantum mechanics, introducing orbital hybridization and resonance to explain bond geometry and strength in more complex molecules, work still built on Lewis's shared electron pair as its basic unit. Irving Langmuir independently extended and popularized the theory during the 1920s and won the 1932 Nobel Prize in Chemistry for that work; Lewis himself, despite originating the idea, was nominated repeatedly but never won a Nobel Prize.