Lesson 2.1 – Dalton’s Postulates & Contributions

In 1803, John Dalton introduced the first scientific atomic model based on experimentation. His model described atoms as tiny, indivisible spheres that combine to form compounds.

Dalton’s Postulates:

1. All matter consists of tiny, indivisible atoms.
2. Atoms of the same element are identical.
3. Atoms combine in fixed whole-number ratios to form compounds.
4. Chemical reactions involve rearrangement of atoms but do not change them.

Strengths & Limitations:

✅ Explained Law of Conservation of Mass & Law of Multiple Proportions.
❌ Did not account for subatomic particles or isotopes.

Quiz 2: Dalton’s Atomic Model

• Identify true or false statements about Dalton’s theory.