The Evolution of The Atomic Theory

Louis De Brogile and Erwin Schrodinger

1887-1987

Louis De Brogile electrons can act like both particles and waves. He also stated that the waves that were produced by electrons produced a standing wave with a set energy, wavelength, and frequency. Schrodinger developed the quantum mechanical model of the atom. This model describes the likelihood of finding an electron in a certain position.

James Chadwick and Max Planck

1858-1974

James Chadwick discovered the neutron in 1932. This discovery led to the discovery of fission and ultimately led to the invention of the atomic bomb. Max Planck discovered quantum theory. Which started out as Planck's theory of black body radiation or the law of heat radiation.

Werner Heinsenberg

1901-1976

Heisenberg calculated the behavior of electrons and other subatomic particles that make up atoms. All of these scientists together gave us the atomic theory that we know today.

Albert Einstein and Neils Bohr

1879-1962

Einstein is most famous for his Theory of Relativity. It stated that energy is equal to mass times the velocity of light squared. This theory became the cornerstone of atomic theory. Bohr suggested that electrons orbited around the nucleus of an atom in specific, discrete orbits and that no other orbit paths were possible.

Robert Milikan and Marie Curie

J.J. Thomson and Ernest Rutherford

1868-1953

1856-1940

Milikan determined the charge of the electron in 1909 with his oil drop experiment. This allowed the mass and charge of an electron to be calculated. Marie Curie proved, through radioactive testing, that atoms of the same element were not divisible.

J.J. Thomson created the cathode ray tube. This is a tube, that when a high voltage current is sent through it and the atoms hit the outside of the tube, it glows. This helped Thomson to test the polarity of the atoms. Ernest Rutherford held many experiments and proved the following things:

-An alpha particle (α=He^+2) is positive

-A Beta particle (β=e-) is negative

-A neutral particle (ϒ) is light

Antoine Lavosier and John Dalton

Democritus

460BC-370BC

1743-1844

The theory of Democritus held that everything is composed of "atoms", which are physically indivisible; that there is empty space between atoms; that atoms are indestructible; have always been, and always will be, in motion.

Lavoisier developed the Law of Conservation. The law states that matter cannot be made or destroyed. He also hints at the rearrangement of matter in reactions. The fact that matter rearranged, but never disappeared. John Dalton however, developed Dalton's Theory which has six parts:

-matter is composed of extremely small particles called atoms

-atoms are indivisible and indestructable

-atoms of a given element are identical in size, mass, and chemical properties

-atoms of specific elements are different than those of other elements

-in a chemical reaction, atoms separate, combine and/or rearrange

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The Evolution of The Atomic Theory