atom history

democritus

300

Democritus claimed that everything was made of atoms, and that they were only physically indivisible but not geometrically. Also he stated that atoms are indestructible. Atoms also always have been and always will be in motion

timespan

Period: 300 to Oct 7, 1932

john dalton

Oct 7, 1803

1. All matter is made up of atoms, they are indivisible and indestructible.

2.” All atoms of a given element are identical in mass and properties” 3.” Compounds are formed by a combination of two or more different kinds of atoms.” 4 “A chemical reaction is a rearrangement of atoms.”

jon daltons atom model

Oct 7, 1803

william Crookes

Oct 7, 1879

invented cathode ray or also known as crookes tubes more info about these rays/tubes can be found here:http://www.crtsite.com/page7.html

Heneri Becquerel

Oct 7, 1896

He had done an experiment by leaving uranium outside to sit in the sun after a while he had brought it inside and put it on a piece of photographic plate already knowing it would leave an image on the plate but his experiment was delayed for the next couple of day due to the cloudy wether so he put the plate and uranium into a drawer until the sun came back out but when he took out the plate and uranium he notice that there was already a picture on the plate he discovered that the piece of miner

Ernest rutherford 1898 1911

Oct 7, 1898

Discovered alpha and beta radiations and did the gold foil experiment to help show the structure of an atom which can be seen here: http://www.rsc.org/chemsoc/timeline/pages/1911.html (experiment)

Rutherford atom model

Oct 7, 1898

J.J Thomson

Oct 7, 1904

“He said that no matter where matter came from, it contained particles that were the same and are smaller than the atoms that matter is formed from.”
His model The Plum Pudding Model can be found here:https: //sites.google.com/site/thomsonsexperiment/jj-thomson-s-atomic-model-and-theory
discovered electrons

Robert Millikan

Oct 7, 1909

He had made The Oil Drop Experiment. The Oil Drop Experiment was designed to find the size of the charge of an electron.

neils bohr

Oct 7, 1913

“Niels Bohr proposed a theory for the hydrogen atom based on quantum theory that energy is transferred only in certain well defined quantities. Electrons should move around the nucleus but only in prescribed orbits. When jumping from one orbit to another with lower energy, a light quantum is emitted. Bohr's theory could explain why atoms emitted light in fixed wavelengths.”

Neils bohr atom model

Oct 7, 1913

Erwin shroödingers model

Oct 7, 1926

Erwin Shroödinger

Oct 7, 1926

took mathematical equations and used them to find the certain position of a electron.

james chadwick

Oct 7, 1932

discovered the neutron in the atom