Gilbert Newton Lewis ForMemRS (October 23, 1875 – March 23, 1946) was an American physical chemist known for the discovery of the covalent bond and his concept of electron pairs; his Lewis dot structures and other contributions to valence bond theory have shaped modern theories of chemical bonding. Lewis successfully contributed to thermodynamics, photochemistry, and isotope separation, and is also known for his concept of acids and bases.G. N. Lewis was born in 1875 in Weymouth, Massachusetts.