John Dalton formulated his atomic theory in the year 1803. This groundbreaking theory proposed that all matter is composed of atoms, which are indivisible and indestructible. Dalton’s theory also introduced the idea that atoms of a given element are identical in mass and properties, and compounds are formed by a combination of two or more different kinds of atoms.
Dalton’s atomic theory laid the foundation for modern chemistry and significantly advanced our understanding of the physical world. His work was based on experimental evidence and provided a clear, systematic explanation of chemical reactions and the nature of matter.