Atoms

By Kendra Falkner
  • 440 BCE

    Democritus

    proposed first idea of the atom: substances made up of tiny indestructible, invisible particles called "atomos."

  • John Dalton

    He proposed atomic theory, with spherical solid masses in motion. Atoms can't be made or destroyed.

  • J.J. Thomson

    Identifies electrons as particles present in every atom

  • Ernest Rutherford

    discovers positively charged nucleus of the atom