Particle Theory of Matter

By mwirth97
  • 370 BCE

    Democritus

    The person who is credited with having conceived of the idea that the world is composed of tiny, indivisible particles is the philosopher Democritus, who lived from 460 to 370 BCE.
  • 322 BCE

    Aristotle

    According to Aristotle (384 - 322 BCE), Democritus believed that the human soul was composed of fire atoms and the body of earth atoms.

  • John Dalton

    Democritus particle theory didn't make much progress, but at the turn of the nineteenth century, it was taken up by English chemist and physicist John Dalton (1766 - 1844).

  • Heinrich Hertz

    In 1887, German physicist Heinrich Hertz discovered the photoelectric effect when he was doing experiments with a spark gap generator. This discovery proved to be far more important than Hertz realized.

  • J.J. Thompson

    English physicist J.J. Thompson discovered the first subatomic particle, the electron, by examining the behavior of cathode rays. His discovery helped explain what constituted the electrical discharge from a conducting plate when you shine light on it – which is the photoelectric effect – but not what causes the discharge nor why the strength of the electrical impulse is related to the light frequency. The solution had to wait until 1914.