Dalton’s atomic theory

Definition

Dalton's atomic theory is a fundamental theory in chemistry stating that all matter is composed of indivisible atoms, each element has identical atoms, and chemical reactions involve rearrangement of these atoms. Proposed by John Dalton in the early 19th century, this theory laid the groundwork for modern atomic science.

5 Must Know Facts For Your Next Test

1. Dalton's atomic theory posits that atoms are indivisible and indestructible.
2. Atoms of the same element are identical in mass and properties according to Dalton.
3. Compounds are formed by a combination of two or more different kinds of atoms.
4. Chemical reactions involve the rearrangement of atoms; no new atoms are created or destroyed.
5. Dalton's work explained laws such as the Law of Conservation of Mass and the Law of Definite Proportions.

Review Questions

• What are the main postulates of Dalton's atomic theory?
• How does Dalton's atomic theory explain the Law of Conservation of Mass?
• What did Dalton propose about the identity and properties of atoms within a single element?

Related terms

Law of Conservation of Mass: A principle stating that mass is neither created nor destroyed during a chemical reaction.

Law of Definite Proportions: A chemical compound always contains exactly the same proportion of elements by mass.

Atom: The smallest unit of an element that retains its chemical properties.