3rd quarter scientists

Father of the modern periodic table

Dmitri Mendeleev

Asserted that all things are composed of four primal elements

earth, air, fire, and water:Empedocles

Concluded that an atom is mostly an empty space

Ernest Rutherford

Proved the presence of neutral subatomic particles

James Chadwick

Proposed the law of definite proportions

Joseph Proust

Formulated the atomic theory

John Dalton

Proposed an atomic model that shows electrons move in concentric orbits around the nucleus

Niels Bohr

Conducted pioneering research on radioactivity

Marie Curie

Discovered radioactivity

Henri Becquerel

Proposed that all matter was continuous and can be further divided into infinitely smaller pieces

Democritus

Suggested the plum pudding model of the atom

J.J. Thomson

Discovered x-rays

Wilhelm Conrad Roentgen

Used X-ray spectra to study atomic structure

Henry Moseley