The atomic theory was first put forward by _______?

The correct answer is John Dalton.

Key Points

• In 1808, John Dalton first proposed an atomic theory of matter and he named it Dalton's atomic theory.
• Dalton’s atomic theory was able to explain the law of conservation of mass, the law of constant composition, and the law of multiple proportions very successfully.

Additional Information

Dalton’s Atomic Theory:

• The smallest indivisible particle of matter is called an atom. The theory states that all matter is composed of indestructible and indivisible building blocks called atoms.
• All atoms of a specific element are identical in mass, size, and other properties. However, atoms of different elements exhibit different properties and vary in mass and size.
• Atoms can neither be created nor destroyed. Furthermore, atoms cannot be divided into smaller particles.
• Atoms of different elements can combine with each other in fixed whole-number ratios in order to form compounds.
• Atoms can be rearranged, combined, or separated in chemical reactions.​