Atomic theory by: Bansari and Riya

Aristotle

384

Stated that all substances are made of 4 elements.
1.Fire
2.Air
3.Water
4.Earth
Earth had a center of the universe he believed

Democritus

460

Proposed that matter is made up of inbreakable particle called atoms. Named smallest piece of matter an atomos, atomos is invisible.His theory is scientificly tested.He was called the "father of Modern Science.

John Dalton

Sep 6, 1766

tranformed democritus ideas of atons into a mordern model.
all mater is made of tiny miscrosope particels called atoms

J.J. Thompson

Dec 18, 1856

Discovered the electron and conducted the cathode ray tube expirement. By adding an electric charge he found that the moving pieces were negative,positive charge.

Robert Millikan

Mar 22, 1868

Detimined the charge and nucular of the electron.
Conduted oil drop experimite by meausuing the effect of an electrical field on very small oil droplets.
from the visocity of the drop and the charge on the plates,he claulated the mass an electron.

Ernest Rutherford

Aug 30, 1871

He discovered the nucleas .The nucleas is made up of mostly of positive and negative charged atoms and mass. The atom contains a nuclei/nucleas piece at the center. The electron orbit the nucleas and the nucleas is made up of protons and is dense.

Neils Bhor

Oct 7, 1885

Proposed the isea that an electron is found only in specific circular paths,orbits around the nuculus.
Reffered to as planatary modle beacuse electrons.
Move around the nuculas like planets around the sun.

Sir James Chadwick

Oct 20, 1891

Confirmed the existence of neutrons in the nucleas.The cloud model is mostly open space. The atom consists of cloudlike regions.The nucleas contains protons and neutrons. The nucleas is the region where electrons in areas of high higher called atomic mass.