History of the Atom

Flashcards about atomic structure, covering the scientists and their contributions to the atomic theory.

Democritus

Greek philosopher who hypothesized about the existence of 'atomos' (indivisible particles) and the 'void' (empty space).

John Dalton

Developed ___Atomic Theory, which stated that all matter is composed of indivisible atoms, atoms of a given element are alike, compounds are formed by combining atoms, and chemical reactions involve rearrangement of atoms.

J.J. Thomson

Discovered electrons using the cathode ray tube experiment and proposed the 'Plum Pudding Model' of the atom.

Eugen Goldstein

Observed positive particles (protons) traveling in the opposite direction of cathode rays.

Ernest Rutherford

Conducted the gold foil experiment, which led to the discovery of the nucleus and the conclusion that most of the atom is empty space.

Niels Bohr

Proposed that electrons exist in specific energy levels or orbits around the nucleus and that they 'jump' between energy levels in a quantum fashion.

James Chadwick

Discovered the neutron, a neutral subatomic particle located in the nucleus with a mass similar to that of a proton.

Werner Heisenberg

Proved that the nucleus contains both protons and neutrons.

Mendeleev and Moseley

Arranged the periodic table by atomic number, based on Moseley's study of x-rays, establishing the periodic law.