18/01/1825 British chemist Edward Frankland is born
Valence Bond Theory, Hybrid Orbitals, and Molecular Orbital Theory
He introduced the concept of chemical valence. Frankland also studied luminous flames and the effects of atmospheric pressure on dense ignited gas, and was one of the discoverers of helium. He was also a member of the second royal commission on the pollution of rivers, and studied London's water quality.