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400
Democritus’ atomic theory
Democritus proposed that everything is made up of indestructible components called atoms. -
Period: 400 to
Development of the Periodic Table
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Isaac Newton’s atomic theory
Isaac Newton discovered that it was gravity that caused things to fall. -
John Dalton’s atomic theory
John Dalton proposed, all elements consist of atoms that were identical and had the same mass. He also discovered that compounds were different elements atoms combined together. -
Michael Faraday
Michael Faraday developed both the laws of electrochemistry. -
Julius Plücker
Julius Plücker, built one of the first gas discharge tubes known as the cathode-ray tube. -
Dmitri Mendeleev
Dmitri Mendeleev created the periodic table. -
James Clerk Maxwell
James Clerk Maxwell made a connection between electromagnetic and light waves and proposed the theory of electromagnetism. -
George Johnstone Stoney
George Johnstone Stoney proposed that electricity was made up of negative particles called electrons. -
Sir William Crookes
Sir William Crookes demonstrates that cathode-rays have a negative charge. -
Eugen Goldstein
Eugen Goldstein discovers canal rays. -
Wilhelm Roentgen
Wilhelm Roentgen discovers x-rays. -
Henri Becquerel
Henri Becquerel discovers radiation. -
Ernest Rutherford
Ernest Rutherford discovers alpha, beta and gamma rays in radiation. -
Marie Curie
Marie Curie discovers radium and polonium. -
Frederick Soddy
Frederick Soddy invented the term ‘isotope’ to describe the unintentional breakdown of radioactive elements. -
Max Planck
Max Planck suggested the idea of quantization to explain how a hot, glowing object emitted light. -
Richard Abegg
Richard Abegg discovers that inert gases have a ‘stable electron configuration. -
Hans Geiger
Hans Geiger invents a machine that can detect alpha particles. -
Henry Moseley
Henry Moseley discovers that the number of protons present in an element determine said elements atomic number. -
Niels Bohr
Niels Bohr proposed that the outer orbit of an atom could hold more electrons than the inner orbit. -
Louis de Broglie
Louis de Broglie discovered that electrons have a wave/particle duality. -
John Cockcroft & Ernest Walton
John Cockcroft & Ernest Walton created the first nuclear reaction. -
Paul Dirac
Paul Dirac proposed the existence of anti-particles. -
James Chadwick
James Chadwick discovers neutrons. -
Lise Meitner, Otto Hahn & Fritz Strassmann
Lise Meitner, Otto Hahn & Fritz Strassmann discovered nuclear fission. -
Glenn Seaborg
Glenn Seaborg discovers eight transuranium elements. -
Enrico Fermi
Enrico Fermi creates first man-made nuclear reactor.
