Timeline Of Atom Discoveries

By siliky
  • 400

    Democritus

    Democritus reinforced his mentor, Leucippus’s atomic theory which stated “the universe is composed of two elements: the atom and and the void in which they exist and move”. Democritus in 465 BC, adopted Leucippus’s idea of atoms, and give the world a basic understanding of the atoms which he hypothesized that all atoms cannot be destroyed, differ in size, shape, temperature and arrangement, are always moving, and are invisible. He created the first atomic model(simply a round sphere which has no

  • Antoine Lavoisier

    Antoine Lavoisier in 1789 described the law of conservation of mass, which states that mass in the universe is neither created nor destroyed. And that means atoms which made up the matter, are neither created nor destroyed.

  • John Dalton

    John Dalton. In 1808, he discovered that all elements are made of atomic weights,deciding on which element it is.He also believes that different elements are made of the same atoms and same thing. It is a fixed ratio, determining in which element it is, with a unique set of ratios. He discovered this by knowing that only certain kinds of gases can be combined in certain proportions. He also made the atomic weights, leading into the periodic time table of elements. He declared that atoms can’t

  • J.J Thompson

    J.J, Thompson. In 1897 he discovered that there is one more part of the atom, the electron. He discovered the electron by conducting of experiments that were made to study the nature of electric discharge in a high vacuum cathode-ray tube. He observed the deflection of the rays by electrically charged plates and magnets as evidence of amd quot bodies much smaller than atoms and quot that he calculated as having a very large value for the charge-to-mass ratio. This proved that the atom is in fac

  • Marie and Pierre

    Marie and Pierre Curie. In 1898, discovered that there is a little bit of uranium in all of the atoms. It is not radioactive, but it could somehow get radioactivated, and the radioactivity could not be determined by the element. It depended on the amount of uranium or thorium inside the atom, and that if order for an element to be radioactive it has to linked directly into the atom.

  • Max Planck

    Max Planck. In the 1900, Max Planck discovered the quantum theory by the Planck's constant which is a group quanta, that the atom were made of other particles. This is really important part, because now we know that the proton and the neutron have to be equal in order for the
    atom to be an atom. We know this in order for us to know that there are 3 parts to an atom. The proton electron and neutron.

  • Ernest Rutherford

    Ernest Rutherford in 1911, proposed a description of atoms as tiny, dense, positively charged core called a nucleus, in which the mass is concentrated, around with light and negative subatomic particle called electron. He contradicted J.J.Thomson’s Plum Pudding model which suggested that electrons and protons are uniformly mixed in an atom. In his gold foil experiment, he tested J.J.Thomson’s hypothesis and disproved the Plum Pudding model and developed Rutherford model.

  • Niels Bohr

    Niels Bohr. In 1913, he discovered how to electrons orbit around the nucleus, and the number of electrons around the nucleus determines the property of the element. He also proved how if an electron is charged or excited it will orbit further away from the nucleus therefore giving it a higher level of energy. He borrowed the conceptions of quantum from Planck and later improvements he improved the structure of the atom. He proved that the electron have a orbit around the nucleus.

  • James Chadwick

    James Chadwick discovered the existence of Neutrons in 1932. Reinforced and contradicted Rutherford’s hypothesis which there could be another subatomic particle that has a mass similar to a proton but has no charge due to the atomic mass is greater than the atomic number. Rutherford called it a neutron and it is a combination of protons and electrons. However, none of these has any evidence to prove. By the time when Irène and Frédéric Joliot-Curie performed a gamma radiation on beryllium’s unus