Atomic Theory By Denae Cash P.d 5 Bogomolova

Democritus

460

(I had to put a specific date)
Born 460 BC
Democritus' theory is that all matter are composed of tiny, indestructable, solid particles called atoms. He also states that atoms could not be subdivided and all spiritual and physical things were composed of atoms.

John Dalton

Sep 6, 1808

(Born 9/6/1766)
John dalton made the billard ball atomic model.
On 1808 his atomic theory Stated:
- All elements are composed of tiny indivisible particles called atoms
- Atoms of the same element are Identicle
-Atoms of different elements can physically mix together or can chemically combine.
- Chemical reactions occur when atoms are separated, joined, or rearranged. Atoms of one element, however, are never changed into atoms of another element as a result of a chemical reaction.

Antoine Henri Becquerel

Dec 15, 1896

(Born Deceber 15, 1852)
On 1896, Antoine Becquerel discovers natural radioactivity when invisible rays from uranium ore darken a photographic plate.

Marie Curie

Nov 7, 1898

(Born November 7, 1867)
In 1898 Marie Curie, along with her husband, both stated that radioactive materials cause atoms to break down spontaneously, releasing radiation in the form of energy and subatomic particles.

J.J. Thomson

Dec 18, 1904

(Born December 18th, 1856)
JJ Thomson discovered the electron on 1897.
On 1904 He creates the "plum pudding" atomic model.

Robert Milikan

Mar 22, 1909

(Born Martch 22, 1868)
In 1909, Robert Milikan determined the charge of an electron with his oil drop experiment.

Ernest Rutherford

Aug 30, 1911

(Born August 30, 1871)
Rutherford proposed the nuclear atom. He also proposed that all of the positive charge and all the mass of an attom occupied a slight volume in the middle. He also stated that most of the volume of an atom was empty space occupied by electrons.

Neils Bohr

Oct 7, 1913

(Born October 7, 1885)
Neils Bohr states that the electrons move around the nucleus in an orbit.

Erwin Schrodinger

Aug 12, 1926

(Born August 12, 1887)
Schrondinger states that the electron in an atom moves in a wave.

James Chadwick

Oct 20, 1932

(Born October 20, 1891)
Chadwick discovered the neutron and proved it to be neutral.