Atomic Theory and Early Models of Matter

What is a primary conclusion of the atomic theory?

Which statement is true regarding atoms of different elements?

What does the Law of Conservation of Mass state?

What did John Dalton propose about atoms?

What was J.J. Thomson's contribution to atomic theory?

What did Ernest Rutherford demonstrate about the atom?

Using a Cathode Ray Tube, what did J.J. Thomson conclude about the light beam?

What is a compound composed of?

Atomic Theory

All matter is composed of atoms.
Atoms are indivisible.
All atoms of the same element are identical.
Atoms of different elements differ from each other.
Compounds form when two or more elements combine.

Law of Conservation of Mass

Matter cannot be created or destroyed, only transformed.
The mass of a substance never changes, but its weight can change due to gravity.

John Dalton

Proposed the Atomic Theory, suggesting that atoms are indivisible and solid, positively charged spheres.
Dalton's experiments determined that substances are composed of specific proportions of atoms.
His model is known as the Billiard Ball Model.

J.J. Thomson

Discovered electrons (negatively charged particles) within a positively charged solid sphere.
Thomson's model is known as the Plum Pudding Model.
Used the Cathode Ray Tube to demonstrate that a positively charged plate attracts a beam of light, proving that the beam must be negatively charged.
He called the negatively charged particles "corpuscles," later named electrons.

Ernest Rutherford

Demonstrated that atoms have a positively charged nucleus containing most of the atom's mass, surrounded by empty negative space.
His experiments used alpha particles to bombard gold foil.

Explore the foundational concepts of atomic theory, including the contributions of John Dalton and J.J. Thomson. Learn about the fundamental principles such as the indivisibility of atoms and the law of conservation of mass. Test your understanding of how these early scientists shaped our current knowledge of matter.