John Dalton

British physicist and chemist John Dalton is best known for developing the atomic theory of elements and molecules, the foundation of modern physical science. While pondering the nature of the atmosphere during a meteorological study in the early 1800s, Dalton deduced the structure of carbon dioxide and proposed that an exact number of atoms constitute each molecule. He held that all atoms of a given element are identical and different from the atoms of every other element. The first to classify elements according to their atomic weights, Dalton set the stage for a revolution in scientific thought. He contributed a great deal to the field of meteorology and also, in 1794, became the first to describe the condition known as color blindness.