Hoyo-MacEachern-Per.1

Aristotle

322

Aristotle didn't believe that in atoms because he thought there was no smaller part of matter. He came up with this theory in 500 B.C. People believed Aristotle's theory because it was easier to understand. Aristotle adopted this theory because of his belief in the gods and how he felt that if the gods didn't create it, it didn't exsist. Aristotle founded the scientific method.

The Atom

Period: 322 to Oct 12, 2011

Democritus

370

One of the founders of the atomic theory. Believed that there are small, indivisible bodies which everything else is composed and that they move about in an infinite space.

John Dalton

Oct 12, 1800

Helped work on the atomic theory. Dalton performed experiments on temperature, gasses, vapours and pressures. He performed these experiments to help better understand his theories.

Henri Becquerel

Feb 12, 1896

While working on a exoermient that exposed uranium-bearing crystal to sunlight, Henri discoered radioactivity. Also, he recieves 3 Nobel Peace Prizes.

JJ Thomson

Apr 30, 1897

Helped discover the electron and isotopes. He discovered this through the cathode rays. He also said that rays were made up of very light and negativley charged particles that were blocking atoms.

Ernest Rutherford

Oct 12, 1899

Founded two types of radio action called thorium and uranium in the experiments he performed. Also, in 1908 he was awarded a nobel peace prize in chemistry for his study in the disentigration of elements and radio substances.

Robert Millikan

Aug 28, 1908

Discovered the measurement of a charge in an electron. While working on an oil drop experiment of an electron, he found the charge-to-mass ratio on the electron and found the measurements.

Niels Bohr

Oct 12, 1922

Helped scientists better understand the atomic structure and quantom mechanic. Niels based his theory off of Rutherford's structure and discovered the quantum mechanic from the model of the structure.

Quantum Model

Oct 12, 1925

A model that shows the area the atom might be located in. Also shows that an atom contains a nucleus, protons and electrons. this model was discovered in 1925 by two men named C.J. Davidson and John H. Germer.

James Chadwick

Oct 12, 1932

Discovered the neutron. Also, in 1992 Chadwick discovered an unkown particle by the lack of the electric charge in the atomic nucleus.

Marie and Pierre Curie

Oct 12, 1996

Discovered Polonium and Radium. Discovered this by studying the field of radiology.