History of the atom

Democritus

His ideas were philosophical and lacked experimental evidence

Democritus

Proposed that atoms ate indivisible, indestructible particles; coined the term "atomos."

Ernest Rutherford

Conducted the gold foil experiment, discovering the nucleus

Ernest Rutherford

Proposed that atoms have a small, dense, positively charged nucleus surrounded by mostly empty space

Erwin Schrodinger

Developed the quantum mechanical model of the atom

Erwin Schrodinger

His work laid the foundation for quantum mechanic

Erwin Schrodinger

Proposed that electrons exist in probability clouds called orbitals

J.J. Thomson

Discovered the electron using the cathode ray tube experiment

J.J. Thomson

Proposed the "plum pudding" model, where electrons are embedded in a positively charged sphere

John Dalton

Atoms cannot be created or destroyed in chemical reactions, only rearranged

John Dalton

Developed the first modern atomic theory based on experimental evidence; stated that atoms of the same element are identical

Niels Bohr

developed the planetary model of the atom

Niels Bohr

His model explained atomic emission spectra using quantized energy levels

Niels Bohr

Suggested that electrons orbit the nucleus in fixed energy levels

Robert Millikan

Measured the charge of the electron using the oil drop experiment