John Dalton's theory regarding atomic theory, published in 1808, incorrectly stated that atoms were the indivisible components of matter. This was later shown to be incorrect when the existence of electrons, protons and neutrons was demonstrated. Dalton was, however, correct in stating that the atom is the smallest particle that is involved in a chemical reaction.
Dalton's theory also stated that atoms combined to form compounds in a ratio of simple whole numbers. This was shown to be incorrect in light of the ratio of atoms in complex organic compounds, such as sucrose, or table sugar, with the molecular formula of C12H22O11. Dalton's atomic theory did, however, correctly recognize the fundamental difference between an atom and a molecule. His work also helped to explain the laws involved when chemicals combine.