Key Concepts in Atomic Theory

Flashcards summarizing key historical figures and concepts in atomic theory.

Democritus

The first person to propose that matter is made of tiny particles called atomos, meaning indivisible.

Law of Conservation of Mass

Developed by Antoine Lavoisier, it states that matter cannot be created or destroyed during a chemical reaction.

Law of Definite Proportions

Proposed by Joseph Proust, it explains that a compound always contains the same elements in the same fixed ratios by mass.

John Dalton

Known as the father of modern atomic theory; proposed that atoms are solid, indivisible spheres and created the Law of Multiple Proportions.

J. J. Thomson

Discovered the electron and proposed the plum pudding model, suggesting electrons are embedded in a positively charged sphere.

Ernest Rutherford

Conducted the gold foil experiment, which showed that atoms have a small, dense, positively charged nucleus.

Niels Bohr

Proposed the planetary model of the atom, where electrons move in fixed orbits around the nucleus.

Werner Heisenberg

Contributed to the electron cloud model, explaining that electrons do not move in exact paths.

Erwin Schrödinger

Expanded on the electron cloud model using mathematical equations to describe electron probabilities.

James Chadwick

Discovered the neutron, a neutral particle located in the nucleus.