The Discovery of Atomic Structure: The Scientists

Democritus

Greek philosopher, Proposed that all matter is made up of tiny, invisible particles called atoms.

Robert Boyle

Regarded as the first modern chemist. defined the element as a substance that cannot be broken down into two or more simpler substances by chemical means.

Joseph Priestley

English educator. Discovered oxygen in 1794.

Antoine Lavoisier

French chemist, proposed the Law of Conservation of Mass. Father of modern chemistry.

Joseph Proust

Proposed Law of Definite Proportions: a given compound always contains the same elements in the same proportions by mass.

John Dalton

proposed the Atomic Theory of Matter

J.J. Thomson

Cathode ray experiment, discovered the electron, proposed the plum pudding model

Robert Millikan

Oil drop experiment, determined the charge of a single electron, determined the mass of the electron

Ernest Rutherford

Gold Foil Experiment, concluded positively charged, dense nucleus. He proposed that the negatively charged electrons orbited the nucleus- Rutherford model

Niels Bohr

Electrons travel around the nucleus- planetary model

Henry Moseley

Named individual positive charged proton. Established that the atomic number of the atom defines the identity of the element

James Chadwick

Discovered the nuetron

Max planck

Electromagnetic radiation

Louis de Broglie

Electron waves

Werner Heisenberg

Heisenberg uncertainty principle

Erwin Schrodinger

Probability of finding an electron at a given place around nucleus- orbitals

Quantum theory

Describes mathematically the wave properties of electrons