History of Atomic Theory Timeline

John Dalton

Apr 22, 1800

Developing the concept of atoms into a scientific theory that is today a foundation of modern chemistry. CONTRIBUTATION TO SCIENCE
Atomic theory, Law of Multiple Proportions and Dalton's Law of Partial Pressures.

Ernest Rutherford

Apr 22, 1897

Ernest Rutherford changed the people think about atoms CONTRIBUTION TO SCIENCE:
Earnest Rutherford's contribution to science was the concept of radioactive half-life, proving that radioactivity involved the transmutation of one chemical element to another, differentiated and named alpha and beta radiation. Proving that alpha radiation is made up of helium ions, discovered the Proton, splitting of an atom and theorised that atoms have their charge concentrated in a very small nucleus.

J.J. Thomson

Apr 30, 1897

J.J. Thomson was the Father of nuclear physics, and discovered the Rutherford model, Rutherford scattering, Rutherford backscattering spectroscopy and the Discovery of protons. CONTRIBUTION TO SCIENCE:
Foathode rays were composed of a previously unknown negatively charged particle, and thus he is credited with the discovry.
AWARDS:
Rumford Medal (1905)
Nobel Prize in Chemistry (1908)
Elliott Cresson Medal (1910)
Matteucci Medal (1913)
Copley Medal (1922)
Franklin Medal (1924)

Marie Curie

Apr 22, 1903

KNOWN FOR:
Conducting the pioneering research on radioactivity. Being the first women to with a Nobel prize. CONTRIBUTION TO SCIENCE:
Theory of radioactivity, techniques for isolating radioactive isotopes and discovering two elements, polonium and radium.

Henry Mosely

Apr 22, 1913

KNOWN FOR:
Contribution to the Physics of Science CONTRIBUTION TO SCIENCE:
Discovering physical laws of the previous empirical and the chemical concept of the atomic number and Moseley's law in X-ray spectra. He helped create a logical order for the periodic table.

Niels Bohr

Apr 23, 1913

Niels Bohr studied under J. J. Thomson, who discouraged his ideas, and under Ernest Rutherford, whose work was expanded by Bohr into a new theory on the structure of the atom in 1913.
Bohr's theory, elaborated and expanded by other physicists, formed the basis for the developing science of quantum mechanics. He is best known for two concepts — the correspondence principle, and the complementarity principle.

Francis Aston

Apr 22, 1922

Francis Aston invented the mass spectrograph, a new type of positive-ray apparatus which uses magnetic and electrostatic fields producing opposite deflections in the same plane to convert molecules into ions, then sorts the ions by to their mass-to-charge ratio. The mass spectroscope proved the existence of isotopes, allowed study of nuclear masses with great precision, and helped lay the foundation for the atomic energy and weaponry.

Erwin Schrodinger

Apr 23, 1926

The introduction of Schrödinger's wave, the mathematical equation of wave mechanics that is still the most widely used piece of mathematics in modern quantum theory. It posits a non-relativistic wave equation that governs how electrons behave within the hydrogen atom. He also worked on analytical mechanics, applications of partial differential equations to dynamics, atomic spectroscopy, color theory, cosmology, counter/detector statistics, eigenvalue problems, and electromagnetic theory.

James Chadwick

Apr 23, 1935

James Chadwick proved the existence of neutrons, the elementary particle without any electrical charge and a fundamental building block of the atom's nucleus.

Murray Gell-Mann

Apr 23, 1953

Developed the concept of strangeness for particles in 1953, In 1961 he proposed the Eightfold way, a new classification system for baryons (heavy subatomic particles) and In 1964 he discovered the quark, omega-minus particles believed to be fundamental building blocks of neutrons, protons, and matter itself.