Atomo

1704 Isaac Newton Proposed a mechanical universe with small solid masses in motion.
1803 John Dalton Proposed an "atomic theory" with spherical solid atoms based upon measurableproperties of mass.
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.
1859  J. Plucker  Built one of the first gas discharge tubes ("cathode ray tube"). 
1869 Dmitri Mendeleev Arranged elements into 7groups 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.
1873 James ClerkMaxwell Proposed electric and magnetic fields filled the void.
1879  Sir William Crookes Discovered cathode rays had the following properties: travel in straight lines from the cathode; causeglass 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 havemass. 
1886 E. Goldstein  Used a CRT to study "canal rays" which had electrical and magnetic properties opposite of an electron. 
1894  G.J. Stoney Proposed that electricity was madeof discrete negative particles he called electrons ". (Link to info on electrons)
1895  Wilhelm Roentgen Using a CRT he observed that nearby chemicals glowed. Further experiments found verypenetrating rays coming from the CRT that were not deflected by a magnetic field. He named them "X-rays". 
1896  Henri Becquerel While studying the effect of x-rays on photographic film, hediscovered some chemicals spontaneously decompose and give off very pentrating rays. 
1897  J.J. Thomson Used a CRT to experimentally determine the charge to mass ratio (e/m) of an electron...