History of the Atom

Democritus

Proposed indivisible atomos concept in ancient Greece.

Alchemy

Ancient practice of transforming earthly elements.

Atomic Theory

Dalton's theory explaining matter's composition with atoms.

Subatomic Particles

Particles smaller than atoms, contradicting Dalton's theory.

Isotopes

Atoms of the same element with different masses.

Billiard Ball Model

Dalton's model depicting atoms as solid spheres.

Cathode Ray Tube Experiment

Thomson's experiment leading to electron discovery.

Plum Pudding Model

Thomson's model showing electrons in a positive sphere.

Oil Drop Experiment

Millikan's experiment measuring electron's mass and charge.

Gold Foil Experiment

Rutherford's experiment revealing atomic nucleus and empty space.

Nuclear Model

Rutherford's model depicting nucleus at atom's center.

Bohr Model

Bahr's model showing electrons in fixed paths.

Neutron

Chadwick's discovery of neutral atomic particles.

Quantum Mechanical Model

Schroedinger/Heisenberg's model describing electron clouds.