History Of The Atom

By Khiya
  • 400 BCE

    Democritus

    Democritus
    Around 400 BC a Greek philosopher Democritus proposed his idea that all matter can be divided into smaller pieces until a single indivisible particle is reached. He later named this particle the atom which means "cannot be cut". He believed that these so called "atoms" are of different sizes, are in constant motion and are separated by empty spaces .
  • 400 BCE

    Aristotle

    Aristotle
    Aristotle rejected the theory of the atom and believed instead all things were made of matter and essence. Aristotle thought matter could be broken down into the four elements which are fire,water,air and earth.Aristotle's views were accepted for 2000 years after his proclamation.
  • Period: 400 BCE to

    History Of The Atom

  • John Dalton

    John Dalton
    John Dalton a English scientist and teacher revived Democritus's theory of the atom. Dalton proposed similar ideas that Democritus did being: all matter is made up of tiny invisible particles called atoms,all atoms of an element are identical,atoms of different elements are different and atoms are rearranged to form new substances in chemical reactions.

  • J.J Thomson

    J.J Thomson
    Thomson added on the atomic theory by stating: Atoms contain negativity charged electrons, since atoms are neutral, the rest of the atom is a positive charged sphere and lastly negatively charged electrons are evenly distributed throughout the atom.

  • Ernest Rutherford

    Ernest Rutherford
    Rutherford was the scientist to perform the gold foil experiment which helped test Thomson model of the atom. The experiment concluded that the center of the atom has a positive charge, the center being the nucleus. The nucleus contains most of the atoms mass but occupies a very small space and most of the atom is empty space. All of this contributed to Rutherford revised model of the atom.

  • Neil Bohr

    Neil Bohr
    Bohr used his years of research to propose the following theory: Electrons orbit the nucleus of the atom much like plants orbit the sun, Each electron in an orbit has a define amount of energy, electrons cannot be between orbits but they can jump between different orbits and lastly each orbit can hold a certain amount of electrons being 2, 8 and 8 in the first, second and third orbits.