From Thoughts About Atoms to the Nuclear Model

From thoughts about atoms to the nuclear model

Aristotle: philosopher, hyle, matter has a continuous force inside it, did not believe in atoms

Democritus: Greek philosopher, thought about atomos, invisible and indivisible

Lavoisier: law of conservation of mass, combustion, and oxygen

Proust: law of definite composition H2O everytime, not HO and H4O sometimes

Dalton: first atomic theory, all matter is composed of indivisible atoms

Davy: said that the color of an atom was dependent on the atom itself. He felt that it was caused by something in the atom. Used cathode rays and electricity, discovered Na, K, Mg, Ca, Sr, and Ba

JJ Thompson: used cathode rays and the effect of a magnetic field to determine the mass and existence of a negative particle, discovered the electron, plum pudding model

Millikan: performed the Oil Drop experiment which determined the magnitude of the negative charge on the electron and the charge to mass ratio, 1/1837 of an H atom

Curie and Becquerel: simultaneously discovered radioactivity

Curie: discovered Ra and Po using pitcheblende

Rontgen: Discovered X-rays

Geiger and Marsden: grad students of Rutherford, designed and performed the Gold Foil Experiment trying to find positive thing in atoms

Rutherford: Interpreted the results of the Gold Foil Experiment which proved: atoms are mostly empty space, that electrons are within that space, and there is a really dense nucleus with protons, which have a positive charge, nuclear model of the atom

Chadwick: working in Rutherford’s lab found the neutron it has no charge and is in the nucleus

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Quantum theory, the behavior of the electron

Bohr: said that electrons have energy and that is why the atoms have a color, explained color by electrons jumping up and down from energy levels, when they fall back down they give off light which we see as a certain color, electrons live in energy levels and move around the nucleus on these paths, called planetary model

Planck: quantified Bohr’s energy and said that the light given off was a photon, and the leap up to excited state was a quantum of energy E=h=frequency

Heisenberg: stated the Uncertainty Principle, you can’t know the speed and location of an electron at the same time

DeBroglie: stated that E=mc2 and E=h were equal, E=h says electrons behave like waves of light, E=mc2 says electrons behave like little particles, called the wave-particle duality of electrons

Schrodinger: developed the wave equation, electron cloud model of an atom, electrons are in regions of probability called orbitals, wave equation gave 4 quantum numbers for hydrogen’s electron which tell us the size, energy, shape, orientation of orbitals and the spin of the electrons within the orbitals

Einstein: E=mc2

Meitner: discovered nuclear fission

Fermi: leader of Manhattan project, first controlled nuclear fission reaction

Bunsen and Kirchhoff: designed the burner and spectroscope to help identify elements based on the energy of electrons and their bright line emission spectra