Helium atom

Atom Timeline

By quinnkitzmiller

  • John Dalton- 1803

    John Dalton- 1803
    John Dalton found out more on the atom than ever before. He spent a great deal of time investigating matter. He is wellknown for his atomic theory. Though it is old, many points in Dalton's theory still stand. Dalton thought that atoms could not be divided. He thought atoms were tiny solid spheres.

  • Sir William Crookes

    Sir William Crookes
    Sir William Crookes investigated cathode ray tubes. When the beams were attached to an electricity source, a glowing beam passed between its metal plates. Crookes studied this beam. Crookes found out that the beam was not just light, but was made of small particles. These particles were made from the metal, inside the beam's negative electrode.

  • J.J. Thomson

    J.J. Thomson
    J.J. Thomson discovered, while testing cathode ray tubes, that every metal produced a beam when attached to electricity. He also discovered that the ray beams were attracted to a positive magnetic field, and repelled by a negative magnetic field. The beams were made of a negative charge. Thomson investigated these charges and found they were much smaller than any known atom. He had found electrons!

  • Ernest Rutherford

    Ernest Rutherford
    Ernest Rutherford experimented on Thomson's theory. He planned to fire fast moving positive particles at a very thin foil of gold atoms. The unexpected happened. Many of the particles passed through the foil, but, some bounced back. Rutherford proposed the idea that atoms were mostly empty space, with a small, positive dense area, in which could block the path of some of the particles.

  • Niels Bohr

    Niels Bohr
    Niels Bohr studied the motion of electrons around the nucleus. He came to the conclusion that electrons taveled in orbits around the nucleus.

  • Sir James Chadwick

    Sir James Chadwick
    Sir James Chadwick discovered the neutron. The neutron has no charge, in other words, is neutral. It is found in the nucleus along with protons.

  • Current Model of the Atom

    Current Model of the Atom
    After Bohr, scientists discovered that electrons do not orbit the nucleus. Electrons behave like waves as well as particles. Our current model of the atom states that electrons are found in the electron cloud.