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Atomic Timeline Project

By brissmelo

  • Atomic model: John Dalton (1808)

    Atomic model: John Dalton (1808)
    1. There are tiny indivisible atoms that makeup matter.
    2. It is impossible to divide, create, or destroy an atom. 2.1 There is no difference in the properties between atoms of the same element. 2.2 There are differences in the properties of atoms of different elements.
    3. Compounds can be formed from atoms of different elements.
    Dalton's atomic theory states that all matter is composed of atoms, based on mass conservation and constant composition.

  • Plum-pudding model: J.J. Thomson (1904)

    Plum-pudding model: J.J. Thomson (1904)
    1. The electrical charge of an atom is neutral. No charge is attached to it.
    2. Atoms have equal positive and negative charges.
    3. During the formation of an atom, positive charges are embedded with negatively charged electrons.
    J.J. Thomson's cathode ray tube studies showed that all atoms contain negatively charged subatomic particles, resulting in the "plum pudding" model.

  • Nuclear model: Ernest Rutherford (1911)

    Nuclear model: Ernest Rutherford (1911)
    1. The majority of the space in an atom is empty.
    2. Atoms contain most of their mass in the center. It is made up of a tiny, dense, and positively charged core known as a nucleus.
    3. There are electrons outside of the nucleus.
    Ernest Rutherford's gold foil experiment showed that an atom is composed of empty space surrounding a tiny nucleus, demonstrating that an atom is mostly composed of empty space.

  • Planetary model: Niels Bohr (1913)

    Planetary model: Niels Bohr (1913)
    1. Each electron orbits the nucleus in a specific orbit with specific energy and size.
    2. An orbit's energy depends on its size. In the smallest orbits, the energy is lowest.
    3. Orbits are where electrons reside. Energy is gained or lost by moving between each shell.
    4. The distance between the nucleus and the electrons increases as energy is gained.
    Bohr's atomic model constrained electrons to specific orbits around the nucleus to explain hydrogen's spectral lines.

  • Quantum Mechanical Model: Erwin Schrödinger (1926-Present)

    Quantum Mechanical Model: Erwin Schrödinger (1926-Present)
    1. The electrons do not orbit the nucleus.
    2. As a cloud of electrons, electrons exist at different energy levels.
    3. Negative charges surround the nucleus in the electron cloud.
    4. Orbital: An area where electrons are likely to be found.
    Erwin Schrödinger's "Schrödinger's cat" experiment involves a cat in a box with a vial of poison, which is superposed in life and death states until it is seen.