Atom

History of th Atomic Theory

By Chappell
  • 500 BCE

    Democritus creating the Atomic Theory

    Democritus creating the Atomic Theory
    Democritus creates the initial Atomic Theory. He stated that there were microscopic particles that make up all matter. He said that they cannot be created, divided or destroyed. In his theory it is also stated that there is empty space between atoms and they are always in constant motion.

  • Dalton's Atomic Theory

    Dalton's Atomic Theory
    John Dalton developed an Atomic Theory similar to that of Democritus'. His theory consisted the fact that all atom can not be created, divided or destroyed. He also suggested that a compound has two or more atoms.

  • J.J. Thomsons Role in the Development of the Atomic Theory

    J.J. Thomsons Role in the Development of the Atomic Theory
    Thomsons greater contribution to the development of the Atomic Theory was the discovering of the electron. He was the first to prove that the atom has several subatomic particles, positive and negative, that balance to give it a neutral charge. He named his atomic model the plum pudding model, the dough being the positively charged sphere and the raisins the electrons. His discovery impacted the way scientists looked at physics as a whole.

  • Rutherford and Bohr's Disproving of the Plum Pudding model

    Rutherford and Bohr's Disproving of the Plum Pudding model
    Ernest Rutherford, a former student of JJ Thomson was the one to disprove his Plum Pudding model. Using what is known as the Gold Foil Experiment, he proved the existence of the positively charged nucleus. His model displayed the atom as negatively charged electrons revolving around a positively charged nucleus.

  • Niels Bohr's Second Atomic Model

    Niels Bohr's Second Atomic Model
    Niels Bohr had a second atomic model that disproved his earlier model. The second theory was Quantum Theory which stated that electrons travel in circles as previously thought but with limitations. Such as the orbits they can occupy and the energy they lose while they jump from one orbit to another. In simpler words he proved the energy levels or quantum states within the electron cloud.

  • James Chadwick's Proving of the Neutron

    James Chadwick's Proving of the Neutron
    James Chadwick was the first to prove the existence of the neutron. During his experiments, Chadwick discovered that if you bombard an atom's nucleus with neutrons it will result in the splitting of the nucleus creating a massive amount of energy. This discovery led to the atomic bomb.