John Dalton

Physicist, Chemist, Meteorologist. Pioneer and developer of modern atomic theory.

[ Born: 1766 / Cumberland, England ]

[ Died: 1844 / Manchester, England. ]

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• Developed modern atomic theory, which has five main points: 1.All elements made of tiny particles called atoms 2.The atoms of a particular element are different to atoms of any other element, and atoms of different elements can be distinguished by having different relative atomic weights. 3. All atoms of a particular element are identical. 4. Atoms of different elements can combine to form chemical compounds. A compound will always have the same relative number of types of atoms. 5. Atoms can neither be created, nor destroyed nor divided into smaller particles in the chemical process. A chemical reaction simply changes how atoms are arranged.
• Dalton’s law of Partial Pressures states that the total pressure exerted by a gaseous mixture is equal to the sum of the partial pressures of each individual component of the gas mixture.
• In honour of this work, the unofficial unit to denote one atomic mass unit is referred to as the Dalton, abbreviated Da.

Trivia - Colour-blindness is often referred to as “Daltonism” in honour of the extensive research done by Dalton on this condition, due to his own colour blindness.

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