History of Chemistry

By Ssachy
  • 460 BCE

    Democritus

    Democritus
    Democritus became the first scientist to create the model of an atom. He was the first one to discover this and named the invisible particles atoms, origination from the "atomos" which means indivisible. His model for the atom was a sphere since he did not have the knowledge to know of the subatomic particles.
  • Period: 460 BCE to

    Atomic History

  • John Dalton

    John Dalton
    Dalton is one of the founders of the modern atomic model. He created the Atomic Theory of Matter which is composed of four ideas that he based off of the law of conversion of mass and Democritus'. He stated that all matter is made of atoms, which can not be destroyed; all atoms of an element have the same mass and properties; that a compound is formed by two or more atoms; and that a chemical reaction is a rearrangement of atoms. Three out of the four ideas are still relevant today.

  • Joseph John Thomson

    Joseph John Thomson
    Thomson was the first chemist to change the appearance of the atoms; at this time, atoms were modeled after solid spheres. He discovered electrons which led him to make the "plum pudding" model. He believed that the atom was mostly positive and that the electrons circled around them.

  • Rutherford

    Rutherford
    Rutherford believed that JJ Thomson's model was incorrect and made a new atomic model. He made the nucleus and stated that the middle was only positive instead of the entire atom. He said the atom was mostly empty space and that the electrons were surrounding a positive nucleus. Rutherford also experimented with radiation through his gold-foil experiments. He found the radioactive element radon and alpha and bete radiation.

  • Bohr

    Bohr
    Bohr is one of Rutherford's students who decided to carry on his legacy. He took Rutherford's original model of the atom but changed the orbit that the electron took around the nucleus. Bohr also added energy levels in the atom which allowed only a certain amount of electrons to fit on each energy level and that the number of electrons present decides the element. There is even an element named after him which is Bohrium.