mahoney.sean.atomictimeline

Atomic History Timeline

__﻿466BC-1700__
=Democritus 460 BC - 371 BC= The Greek philosopher Democritus suggested that all matter was formed of different types of tiny discrete particles and that the properties of these particles could not be destroyed.

=**Aristotle** 384-322 BC=

He developed the theroy that all matter consisted of four elements: Earth, Air, Water and Fire.
=__1700-1800__= =﻿=

[[image:http://upload.wikimedia.org/wikipedia/commons/thumb/e/e9/John_Dalton.jpg/430px-John_Dalton.jpg width="240" height="333" align="left" caption="external image 430px-John_Dalton.jpg"]]
John Dalton discovered that all matter is made of atoms which are indestrutible. All atoms of a given element are identical in mass and properties. he also realized compounds are formed by a combination of two or more different kinds of atoms and chemical reactions is a rearrangement of atoms.

==He established the Law of Conservation of Mass through experiments. This statesthat in any chemical reaction, mass is conserved: Matter is neither created nor destroyed; only the form of the matter is altered.==

=__1800-1875__= = =

[[image:http://www.mindspring.com/~banchero1/ieee/roentgen.gif width="221" height="266" caption="external image roentgen.gif"]]
German Physisist who produced electromagnetic radiation and ultimately discovered x-rays. He later won a Nobel Prize.

=
She was mostly known for her work with radioactivity. she was the only person to win a Nobel prize in two different sciences. she is also a badass chemist because she was a woman and it was uncommon for women to make discoveries like she did.=====

=__1875-1900__=

J.J. Thompson 1856- 1940

JJ Thompson created the plum pudding model of the atom.

Ernest Rutherford 1871-1937


Rutherford became known as the “father” of nuclear physics. In 1907, he conducted the experiments that discovered the nuclear nature of atoms. He discovered the Rutherford model of the atom having a very small positively charged nucleus orbited by electrons. He is also responsible for the “gold-foil” experiment.

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===Millikan came up with the measurement of the electric charge. He also compared the intensity of cosmic rays at various latitudes and altitudes which helped scientist study how the earth's magnectic field deflects cosmic rays as they arrive from outer space.===

=__1900-1950__= ====James Chadwick Chadwick is most known for proving the existence of neutrons. he later won a nbel prize for this discovery. His discovery led toward the creation of the atomic bomb====

made fundemental contributions to quantum mechanics, but is most widely known for his develepmentof the Heisenburg uncertantyt princibles.
===Niels Bohr He suggested the ectrons must be orbiting the nucleous in fixed energy levels. he is also most known for the development of his model of the atom.===