Atomic Theory

By nivana1
  • 410

    Aristotle

    Aristotle believed in the four elements earth,fire, water,air and that no matter how many times you cut a matter in half you will get a smaller piece.
  • Period: 410 to

    timeline of contributers to the atomic theory

    These particular scientists were contributing to the atomic theory from 410 B.C.E. to the 1900s C.E..
  • 440

    The Greek philosopher, Democritus

    Democritus were one of the first scientists to discover the ultimate particle which he called "atomos." He believed that everything in the world were made out of atoms which were indivisable and microscopic.

  • Robert Boyle

    Aristotle proposed that matter consisted of four elements fire, water, air, earth and the three paracelsian elements of salt,sulfur and mercury.

  • Isaac Newton

    Isaac newton believed that a mechanical universe with small, solid massesin motion.He also suggested that the atoms were held together by strong attractions/forces to each other.

  • Joseph Louis Proust

    Joseph Proust produced the law of Constant Composition in 1799. The law of Constant Composition states that in a pure compound, the elements are always present in the same definite proportion by mass.

  • Joseph Priestly

    Joseph Priestly discovered oxygen which is essential to provide life on the planet. He called oygen "dephlogisticated air."

  • Antoine Lavoiser

    Antoine Lavoiser was called the "Father of Chemistry."He made the law of conservation of mass.

  • John Dalton

    John Dalton made the law of multiple porprotions and proposed a system of symbols to represent atoms of various elements. Also, he discovered equivalent masses and color blindness.

  • Michael Faraday

    Michael Faraday was an english chemist and physicist who realized the importance of electric attractions in compounds. He varified the idea that electric forces held the atoms together.

  • Dimitri Mendeleev

    Dimitri Mendeleev
    Dimitri Mendeleev invented the Periodic table that arranged all the elements that were discovered according to increasing atomic weight.

  • J.J. Thompson

    J.J Thompson discovered negatively charged electron by using his invention the cathode ray tube.He calculated the charge to mass ratio for the electron.
    e/m = -1.76 x 108 coulombs/g
    He then discovered protons and the ratio was....
    e/m = +9.58 x 104 coulombs/g

  • Earnest Rutherford

    Earnest Rutherford proposed the nucleus which occupied a small volume at the center of the atom. Also that most of the volume of the atom was empty space which was occupied for electrons. After, Rutherford discovered the neutron.

  • James Chadwick

    James Chadwick discovered the neutron as a team with Rutherford since they were great partners and worked together.

  • Francis Aston

    Francis Aston made an invention called the mass spectograph in 1920. He observed three different types of hydrogen atoms. He found other atoms that had a mass of 2 and 3 not just 1. His work assisted rutherford ffrom ddiscovering the neutron.