Atom Timeline

By abcdefghijklmnopqrstuvwxyz1606
  • 400 BCE

    Democritius

    Democritius
    Democritus proposed that matter consisted of indivisible atoms that could not be broken down. In between atoms would be a vacuum.
  • 335 BCE

    Empedocles

    Empedocles
    Empedocles proposes that air is not nothing and takes up space, creating the Cosmogenic Theory of 4 basic elements
  • 335 BCE

    Aristotle

    Aristotle
    Aristotle did not believe in vacuums, and added 4 more elements to the cosmogenic theory: hot, dry, wet, and cold. He established the Lyceum in which his science was believed for 2000 years.

  • Sir Francis Bacon

    Sir Francis Bacon
    Sir Francis Bacon established the scientific method which is experimentation necessary for all theories.

  • Robert Boyle

    Robert Boyle
    Robert Boyle questioned the cosmogenic theory, proposing that an element is a pure substance that could not be broken down, and that elements can combine to create compounds.

  • Joseph Priestly

    Joseph Priestly
    Joseph Priestly discovered oxygen and found that air was a mixture, not a single element. He also believed that elements contained a flammable substance called plogiston.

  • Henry Cavendish

    Henry Cavendish
    Henry Cavendish discovered hydrogen, which mixed with oxygen to create water, proving water is a mixture and not an element.

  • Antoine de Lavoisier

    Antoine de Lavoisier
    Antoine de Lavoisier disproved that elements contained phlogiston, and identified 23 new elements, which were pure substances that could not be broken down. He also established the Law of Conservational Mass which was that matter could not be destroyed.

  • Michael Faraday

    Michael Faraday
    Michael Faraday experimented with chemical changes and discovered electricity. He found charged atoms called ions, and proposed that matter had a positive or negative charge. Opposite charges attract holding atoms together, whereas like charges repel.

  • JJ Thomson's Atomic Model

    JJ Thomson's Atomic Model
    JJ Thomson proposed the Plum Pudding model for the atom, proposing a sphere with positive charges, and within the sphere there are negative charges, fitting Michael Farraday's proposal of positive and negative mass

  • James Chadwick

    James Chadwick
    James Chadwick discovered the neutron which balances out positively charged and negatively charged matter