Dalton’s atomic theory is the oldest theory about the atom. In 1808, John Dalton published his theory, which was composed of several postulates that were built based on his experiments and laws of chemical combination. A number of scientists later contributed to the development of modern atomic theory, which is different from Dalton’s atomic theory and has more advanced facts about the atom and its behavior. The key difference between Dalton’s Atomic Theory and Modern Atomic Theory is that the structure and properties of atom according to Dalton’s theory are different from the structure and properties proposed by the modern atomic theory.
Difference :
Dalton’s atomic theory is a theory about indivisible particles called atoms which are the smallest particles of all matter. Modern atomic theory is the theory that explains the fully detailed structure of an atom.
Structure of Atom
According to Dalton’s atomic theory, atoms are indivisible particles. Modern atomic theory says that atoms are composed of subatomic particles; protons, electrons, and neutrons.
Isotopes
Dalton’s theory does not explain details about isotopes. It states that all atoms of the same element are identical. Modern atomic theory explains details about isotopes having a different number of neutrons and the same number of protons.
Electrons
Dalton couldn’t give details about electrons. Modern atomic theory explains the location, reactions, and behavior of electrons.
Chemical Reactions
Dalton’s atomic theory explains that atoms are the smallest particle that can be engaged in reactions. Modern atomic theory states that subatomic particles can participate in reactions.