History of an Atom

Democritus

460

His mentor, Leucippus, orginally came up with the atomic theory, but then it was adopted by Democritus.
But he discovered ...
The atom.
Atoms are solid but invisible.
Atoms difer in size, shape, mass, position, and arragement.
He purposed matter was made into tiny pieces that couldn't be minized from that size.

John Dalton

Jan 1, 1803

Dalton came up with an atomic theory called Dalton’s Law of Partial Pressures that included information about elements that incldued:
- Items are made of extremely small particles called atoms.
- Atoms of a given element are identical in size, mass, and other properties. Atoms of different elements differ in size, mass, etc.
- Atoms cannot be subdivided, created, or destroyed.

Marie Curie

Apr 13, 1903

Marie Curie was a very important woman in scientific history. Aside from discovering radium and polonium, she first woman to win the Nobel Prize in Physics in 1903 and Chemistry in 1911. Marie's contributions to the study of radium and radiation was an instrumental technology for the future development of the atomic bomb. Marie was the only woman ever to win mulitple Noblie Prizes.

Thomas Thomson

Sep 30, 1903

Thomas wrote a lot about atoms and had many theories about them. His writings contributed to the early spread of Dalton's atomic theory. He was the inventor of the saccharometer and gave silicon its name. Thomson suggested a model of the atom as a sphere of positive matter in which electrons are positioned by electrostatic forces. Thomas Thomson had many students too, including chemist, Ernest Ruthford. Thomas introdcued the spectrograph and that helped him figure out what isotopes are.

Ernest Rutherford

Nov 4, 1911

Known as the father of nuclear physics
He discovered alpha and beta rays, set forth the laws of radioactive decay, and identified alpha particles as helium nuclei. Most important, he postulated the nuclear structure of the atom
Established that the nucleas is very dense, small and positively charged and that electrons are located outside the nucleas.
He went to Cambridge University, where he became J. J. Thomson's first graduate student at the Cavendish Laboratory.

Niels Bohr

Sep 30, 1922

Henry Mosely who was a scientist to help Bohr, proposed that the atomic number of an element is equal to the number of protons in the nucleus and based the periodic table on atomic number instead of atomic mass.
Discovered atomic structure.
Bohr's model has a more accurate amount of protons and electron.
Has a nucleus in the middle with protons in it and electrons on the rings in orbit around the nucleus.
Professor of Physiology at Copenhagen University.

James Chadwick

Jan 1, 1932

Erwin Schrodinger shelped Chadwick a little with his experience
Also studied under Ernest Rutherford
Discovered existence of neutrons
Improved Bohr's model because of neutrons
Has a nucleus in the middle with protons and neutrons in it and electrons on the rings in orbit around the nucleus