Atmomic Model Contributors

Democritus

150

Democritus believed that all matter consisted of tiny particles called atoms. He had no tools or equipment to test his theory. His theory was based just on "mind expieriments" such as
imagining a large piece of matter and gradually cutting it into smaller and smaller pieces, finally reaching the smallest piece.

Aristotle

200

Ariswtotle believed that there were only 4 elements, (air,water,fire,earth) and that these made up all matter. Like Democritus, Aristotle could only prove his theory based on his own knowledge.

John Dalton

Oct 30, 1803

Dalton formed the atomic theory, which states that all matter is composed of tiny, indestructible particles called atoms that are all alike and have the same atomic weight. Dalton performed experiments that led him to notice that certain gases maintained the same ratios of mixture regardless of amount. Leading him to form his theory.

Joseph John (J.J) Thompson

Oct 30, 1856

Thompson proposed that atoms are made of even smaller particles which he called "corpuscles". He conducted experiments using a sealed glass tube that hadametal disc at either end. Electricity was connected to the metal discs and when turned on, it created a negative charge at one end and a positive charge at the other end. A glowing beam was created in-between them. This lead Thompson to believe that atoms were even smaller than thought to be.

Ernest Marsden

Feb 19, 1889

Physicicst Ernest Marsden was known for heping Ernest Rutherford and his discovery of the new and improved atom, using the Gold foil experiment. As one of Rutherford's students, Rutherford asked one of his students being Mardsen to help him on this experiment and gather research.

Hantaro Nagaoka

Oct 31, 1904

Hantaro Nagaoka presented a theory based on the thought that electrons revolve around the positively charged center of the atom like the rings of Saturn. Nagaoka worked with J.J Thompson and Ernest Rutherford.

Ernest Rutherford

Oct 30, 1911

Rutherord discovered that uranium puts out fast moving particles that have a positive charge. He proposed that the mass and charge at any location in the gold would be too small to change the direction of an alpha particle based on Thomson's model of the atom.

Niels Bohr

Oct 30, 1913

He created a model of atoms that forced on electrons such as thier arrangement in an atom and that electrons travel in discrete (detachted or individual) orbit around the atoms nucleus. He looked at similar stuctures of the solar system. This was an improvement on the earlier plum-pudding model, cubic model, and the Saturnian model.

Henry Mosely

Nov 1, 1914

Studying under Ernest Rutherford, Moseley developed the application of X-ray spectra to study atomic structure by measuring the wavelengths of the x-rays given off by certain metals. Moseley was able to determine the number of positive charges in the nucleus of an atom. This was the first concept of the atomic number

Louis de Broglie

Nov 1, 1924

Brogile said moving particles such as electrons have some properties of waves.To try and prove his theory he and his lab partneers did so by shooting electrons at special coated nickles.

Erwin Schrodinger

Nov 1, 1926

Erwin developed mathematical equations to describe the motion of electrons in atoms. His model was developed into a electron cloud.

James Chadwick

Nov 1, 1932

James was famous for his discovery of the neutron contributing to our understanding of the atom.Chadwick discovered the neutron. It was named this because of the lack of electric charge, which was previously an unknown particle in the nucleus of an atom.

Enrico Fermi

Nov 1, 1942

Fermi is credited with conducting the first controlled chain reaction releasing energy from the atoms nucleus.