15 contributers to the atomic theory

Isaac Newton

Apr 23, 1704

Proposed a mechanical universe with small solid masses in motion

John Dalton

Apr 23, 1803

Proposed an "atomic theory" with spherical solid atoms based upon measurable properties of mass.

Michael faraday

Apr 23, 1832

Studied the effect of electricity on solutions, coined term "electrolysis" as a splitting of molecules with electricity, developed laws of electrolysis. Faraday himself was not a proponent of atomism.

J. Plucker

Apr 23, 1859

Built one of the first gas discharge tubes ("cathode ray tube").

Dmitri Mendeleev

Apr 23, 1869

Arranged elements into 7 groups with similar properties. He discovered that the properties of elements "were periodic functions of the their atomic weights". This became known as the Periodic Law.

James clerk Maxwell

Apr 23, 1873

Proposed electric and magnetic fields filled the void.

Sir William crookes

Apr 23, 1879

Discovered cathode rays had the following properties: travel in straight lines from the cathode; cause glass to fluoresce; impart a negative charge to objects they strike; are deflected by electric fields and magnets to suggest a negative charge; cause pinwheels in their path to spin indicating they have mass.

E. Goldstein

Apr 23, 1886

Used a CRT to study "canal rays" which had electrical and magnetic properties opposite of an electron.

G.J. Stoney

Apr 23, 1894

Proposed that electricity was made of discrete negative particles he called electrons ". (Link to info on electrons)

Wilhelm roentgen

Apr 23, 1895

Using a CRT he observed that nearby chemicals glowed. Further experiments found very penetrating rays coming from the CRT that were not deflected by a magnetic field. He named them "X-rays".

Henri Becquerel

Apr 23, 1896

While studying the effect of x-rays on photographic film, he discovered some chemicals spontaneously decompose and give off very pentrating rays.

J.J. Thompson

Apr 23, 1897

Used a CRT to experimentally determine the charge to mass ratio (e/m) of an electron =1.759 x 10 8 coulombs/gram. Studied "canal rays" and found they were associated with the proton H + .

Rutherford

Apr 23, 1898

Studied radiations emitted from uranium and thorium and named them alpha and beta.

Marie Sklodowska Curie

Apr 23, 1898

Studied uranium and thorium and called their spontaneous decay process "radioactivity". She and her husband Pierre also discovered the radioactive elements polonium and radium.

Democritus

Mar 2, 2022

Democritus stated "by convention bitter, by convention sweet, but in reality atoms and void"