Timeline of the Atom

Democritus, Greece

470

Proposed that all matter is made of almost infinite indivisible particles which differ from each other in form, position, and arrangement http://scienceworld.wolfram.com/biography/Democritus.html

Isaac Newtown, England

Jan 1, 1704

Suggested that atoms were held together by attractions that we call forces http://scienceworld.wolfram.com/biography/Newton.html

John Dalton, England

Jan 1, 1803

Proposed an "atomic theory" with spherical solid atoms based upon measurable properties of mass and also explained what atoms are and devised the modern atomic theory.
http://scienceworld.wolfram.com/biography/Dalton.html

George Johnstone Stoney, Ireland

Jan 1, 1894

Proposed that electricity was made of discrete negative particles he called electrons;introduced us to the basic concept of negative charge http://atomictimeline.net/index.php

Joseph John Thomson, England

Jan 1, 1897

Discovered electron and isotopes; proved atoms had subatomic atoms which allowed us to know the existence of subatomic atoms particles through cathode rays
http://scienceworld.wolfram.com/biography/Thomson.html

Max Planck, Germany

Jan 1, 1900

Founder of the quantum theory which revolutionised our understanding of atomic and subatomic processes
http://scienceworld.wolfram.com/biography/Planck.html

Hantora Nagaoka, Japan

Jan 1, 1903

Created a model of an atom(though slightly incorrect) based on the solar system analogy which helped us understand the structure of the atom http://atomictimeline.net/index.php

Robert Andrews Milikan, America

Jan 1, 1909

Using the oil drop experiment he measured the charge and the mass of the electron http://en.wikipedia.org/wiki/Robert_Andrews_Millikan

Ernest Rutherford, British- New Zealand

Jan 1, 1911

Established that the nucleus was: very dense,very small and positively charged. He also assumed that the electrons were located outside the nucleus http://en.wikipedia.org/wiki/Ernest_Rutherford

Henry Gwyn-Jeffreys Moseley, England

Jan 1, 1914

Organised the periodic table based upon the atomic number instead of atomic mass http://wapedia.mobi/en/Henry_Moseley

Niels Bohr, Denmark

Jan 1, 1922

Expanded upon Rutherford’s theory by proposing that electrons travel only in certain successively larger orbits which he built the Bohr model of the atom's shell http://www2.lucidcafe.com/lucidcafe/library/95oct/nbohr.html

James Chadwick, England

Jan 1, 1932

Using alpha particles discovered a neutral atomic particle with a mass close to a proton. Thus was discovered the neutron.
http://atomictimeline.net/index.php