Scientists timeline

Democritus

400

Democritus found the atom.All atoms are indivisble, Atom derives from atomos. Atomos is greek for indivisible. http://www.perseus.tufts.edu/GreekScience/Students/Marc/short_paper.html

Aristotle

460

Said there was 4 elements: earth, air, water, and fire https://the-history-of-the-atom.wikispaces.com/Aristotle

Isaac Newton

Jan 1, 1704

Proposed a mechanical universe with small solid masses in motion. http://historyoftheatomictheory.weebly.com/isaac-newton.html

John Dalton

Jan 1, 1799

1st atomic theory
Billiard ball model
Atoms of an element are similar
Atoms of each element are different from each other

Micheal Faraday

Jan 1, 1832

splitting of molecules with electricity, developed laws of electrolysis Resources:
http://www.chemteam.info/Chem-History/Faraday-Chlorine-1823.html

Julius Plücker

Nov 12, 1859

Built one of the first cathode ray tube

Dmitri Mendeleev

Nov 12, 1869

Arranged elements into 7 groups with similar properties

James Maxwell

Jan 1, 1873

Proposed electric and magnetic fields filled the void

James Clerk Maxwell

Nov 12, 1873

Proposed electric and magnetic fields filled the void.

Eugen Goldstein

Nov 12, 1886

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

G.J. Stoney

Nov 12, 1894

Proposed that electricity was made of discrete negative particles called electrons Resources:
http://www.rds.ie/index.jsp?a=806&n=245&p=182

Wilhelm Röntgen

Jan 1, 1895

Using a cathode ray tube he observed that nearby chemicals glowed. Further experiments found very penetrating rays coming from the cathode ray tube that were not deflected by a magnetic field Resources:

JJ Thomson

Jan 1, 1897

Discovered the electron
Used cathode ray tube
Plum pudding model

Marie Curie

Jan 1, 1898

Studied uranium and thorium and called their spontaneous decay process "radioactivity".

Max Planck

Jan 1, 1900

Developed the quantum theory Resources:
http://www.nobelprize.org/nobel_prizes/physics/laureates/1918/planck-bio.html

Hantaro Nagoaka

Jan 1, 1903

assumed that the atom is a large, massive, positively charged sphere, encircled by very many light-weight, negatively charged electrons

Richard Abegg

Nov 12, 1904

Discovered that inert gases had a stable electron configuration which lead to their chemical inactivity

Hans Geiger

Jan 1, 1906

Developed an electrical device that counted the alpha particles. Resources:
http://inventors.about.com/od/gstartinventors/p/Hans_Geiger.htm

Albert Einstein

Jan 1, 1908

Said that mass = speed of light squared

R.A. Millikan

Jan 1, 1909

Oil drop experiment determined the charge (e=1.602 x 10 -19 coulomb) and the mass (m = 9.11 x 10 -28 gram) of an electron

Rutherford

Jan 1, 1911

Discovered protons, nucleus
Concluded the atom was mostly space

Bohr

Jan 1, 1913

Electrons are placed in energy levels surrounding the nucleus
Student of Rutherford

Francis Aston

Jan 1, 1919

Discovered the existence of isotopes through the use of a mass spectrograph

Phillip Lenard

Jan 1, 1921

Lenard proposed the model of an atom to have each positive and negative charge bound together. He also did a large amout of work with cathode rays.

Chadwick

Jan 1, 1932

Discovered the neutron
Used nuclear fission

Enrico Fermi

Nov 12, 1942

Conducted the first controlled chain reaction releasing energy from the atoms nucleus Resources:
http://www.nobelprize.org/nobel_prizes/physics/laureates/1938/fermi-bio.html