Atomic Structure History timeline

Jan 1, 1704

Isaac Newton Proposed a mechanical universe with small solid masses in motion.

http://atomictimeline.net/index.php
Sep 17, 1803

John Dalton Proposed an "atomic theory" with spherical solid atoms based upon measurable properties of mass.
Sep 17, 1832

Michael Faraday 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.
Sep 17, 1839

J. Plucker Built one of the first gas discharge tubes ("cathode ray tube").
Sep 17, 1869

Dmitri Mendeleev 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.
Sep 17, 1873

James Clerk Maxwell Proposed electric and magnetic fields filled the void.
Sep 17, 1879

Sir William Crookes 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 nega
Sep 17, 1886

E. Goldstein Used a CRT to study "canal rays" which had electrical and magnetic properties opposite of an electron.
Sep 17, 1894

G.J. Stoney Proposed that electricity was made of discrete negative particles he called electrons ". (Link to info on electrons)
Sep 17, 1895

Wilhelm Roentgen 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".
Sep 17, 1896

Henri Becquerel While studying the effect of x-rays on photographic film, he discovered some chemicals spontaneously decompose and give off very pentrating rays.
Sep 17, 1897

J.J. Thomson Used a CRT to experimentally determine the charge to mass ratio (e/m) of an electron =1.759 x 10 8 coulombs/gram. 1897 J.J. Thomson Studied "canal rays" and found they were associated with the proton H + .
Jan 17, 1898

Rutherford Studied radiations emitted from uranium and thorium and named them alpha and beta.
Sep 17, 1898

Marie Sklodowska Curie Studied uranium and thorium and called their spontaneous decay process "radioactivity". She and her husband Pierre also discovered the radioactive elements polonium and radium.
Sep 17, 1900

Soddy Observed spontaneous disintegration of radioactive elements into variants he called "isotopes" or totally new elements, discovered "half-life", made initial calculations on energy released during decay.
Dec 17, 1900

Max Planck used the idea of quanta (discrete units of energy) to explain hot glowing matter.
Sep 17, 1903

Nagaoka Postulated a "Saturnian" model of the atom with flat rings of electrons revolving around a positively charged particle.
Sep 17, 1904

Abegg Discovered that inert gases had a stable electron configuration which lead to their chemical inactivity.
Sep 17, 1905

Albert Einstein Published the famous equation E=mc 2
Sep 17, 1906

Hans Geiger Developed an electrical device to "click" when hit with alpha particles.
Sep 17, 1909

R.A. Millikan 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.
Sep 17, 1911

Ernest Rutherford Using alpha particles as atomic bullets, probed the atoms in a piece of thin (0.00006 cm) gold foil . He established that the nucleus was: very dense,very small and positively charged. He also assumed that the electrons were located out
Sep 17, 1914

H.G.J. Moseley Using x-ray tubes, determined the charges on the nuclei of most atoms. He wrote"The atomic number of an element is equal to the number of protons in the nucleus". This work was used to reorganize the periodic table based upon atomic number
Sep 17, 1919

Aston Discovered the existence of isotopes through the use of a mass spectrograph.
Sep 17, 1922

Niels Bohr Developed an explanation of atomic structure that underlies regularities of the periodic table of elements. His atomic model had atoms built up of sucessive orbital shells of electrons.
Sep 17, 1923

de Broglie Discovered that electrons had a dual nature-similar to both particles and waves. Particle/wave duality. Supported Einstein.
Sep 17, 1927

Heisenberg Described atoms by means of formula connected to the frequencies of spectral lines. Proposed Principle of Indeterminancy - you can not know both the position and velocity of a particle.
Sep 17, 1929

Cockcroft / Walton Built an early linear accelerator and bombarded lithium with protons to produce alpha particles
Sep 17, 1930

Schrodinger Viewed electrons as continuous clouds and introduced "wave mechanics" as a mathematical model of the atom.
Sep 17, 1930

Paul Dirac Proposed anti-particles . Anderson discovered the anti-electron (positron) in 1932 and Segre/Chamberlain detected the anti-proton in 1955..
Sep 17, 1932

James Chadwick Using alpha particles discovered a neutral atomic particle with a mass close to a proton. Thus was discovered the neutron.
Sep 17, 1938

Lise Meitner, Hahn , Strassman Conducted experiments verifying that heavy elements capture neutrons and form unstable products which undergo fission. This process ejects more neutrons continuing the fission chain reaction.
Period: Sep 17, 1941 to Sep 17, 1951

Glenn Seaborg Synthesized 6 transuranium elements and suggested a change in the layout of the periodic table.
Sep 17, 1942

Enrico Fermi Conducted the first controlled chain reaction releasing energy from the atoms nucleus.

Isaac Newton Proposed a mechanical universe with small solid masses in motion.

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

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

Dmitri Mendeleev 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 Proposed electric and magnetic fields filled the void.

Sir William Crookes 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 nega

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

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

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

J.J. Thomson Used a CRT to experimentally determine the charge to mass ratio (e/m) of an electron =1.759 x 10 8 coulombs/gram. 1897 J.J. Thomson Studied "canal rays" and found they were associated with the proton H + .

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

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

Soddy Observed spontaneous disintegration of radioactive elements into variants he called "isotopes" or totally new elements, discovered "half-life", made initial calculations on energy released during decay.

Max Planck used the idea of quanta (discrete units of energy) to explain hot glowing matter.

Nagaoka Postulated a "Saturnian" model of the atom with flat rings of electrons revolving around a positively charged particle.

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

Albert Einstein Published the famous equation E=mc 2

Hans Geiger Developed an electrical device to "click" when hit with alpha particles.

R.A. Millikan 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.

Ernest Rutherford Using alpha particles as atomic bullets, probed the atoms in a piece of thin (0.00006 cm) gold foil . He established that the nucleus was: very dense,very small and positively charged. He also assumed that the electrons were located out

H.G.J. Moseley Using x-ray tubes, determined the charges on the nuclei of most atoms. He wrote"The atomic number of an element is equal to the number of protons in the nucleus". This work was used to reorganize the periodic table based upon atomic number

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

Niels Bohr Developed an explanation of atomic structure that underlies regularities of the periodic table of elements. His atomic model had atoms built up of sucessive orbital shells of electrons.

de Broglie Discovered that electrons had a dual nature-similar to both particles and waves. Particle/wave duality. Supported Einstein.

Heisenberg Described atoms by means of formula connected to the frequencies of spectral lines. Proposed Principle of Indeterminancy - you can not know both the position and velocity of a particle.

Cockcroft / Walton Built an early linear accelerator and bombarded lithium with protons to produce alpha particles

Schrodinger Viewed electrons as continuous clouds and introduced "wave mechanics" as a mathematical model of the atom.

Paul Dirac Proposed anti-particles . Anderson discovered the anti-electron (positron) in 1932 and Segre/Chamberlain detected the anti-proton in 1955..

James Chadwick Using alpha particles discovered a neutral atomic particle with a mass close to a proton. Thus was discovered the neutron.

Lise Meitner, Hahn , Strassman Conducted experiments verifying that heavy elements capture neutrons and form unstable products which undergo fission. This process ejects more neutrons continuing the fission chain reaction.

Glenn Seaborg Synthesized 6 transuranium elements and suggested a change in the layout of the periodic table.

Enrico Fermi Conducted the first controlled chain reaction releasing energy from the atoms nucleus.