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400
Democritus
''by convention bitter, by convention sweet, but in reality atoms and void" -
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"). -
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 negative charge; cause pinwheels in their path to spin indicating they have mass. -
Sir William Crookes
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".