a timeline

By jacky.huang

  • issac 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").

  • lothar meyer

    Classified elements into six families by their valence.

  • 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.

  • 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 ".

  • willhelm 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. Hear Thompson talk about the size of an atom. Examine Thompson's 3 experiments to verify atoms had parts.

  • J.J. Thomson

    Studied "canal rays" and found they were associated with the proton H + .

  • Rutherford

    Studied radiations emitted from uranium and named them alpha and beta.He estimated atom size and concluded mass was concentrated in the nucleus.

  • 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. Marie was the first person awarded two Nobel prizes. Video of Marie Curie in her lab in 1923.

  • 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.