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Democritus
He hypothesized that atoms: can't be destroyed; differ in size,shape and temperature; and they are always moving. He also believed that there is an infinite number of atoms. -
John Dalton
Dalton Atomic theory
1. Elements are made of extremely small particles called atoms
2. atoms of a given element are identical in size, mass, and other properties; atoms of different elements differ in size, mass, and other properties.
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3. Atoms cannot be subdivided ,created or destroyed.
4. Atoms of different elements combine in simple whole-number ratios to form chemical compounds.
5 In Chemical reactions, atoms are combined, separated, or rearranged.
He created the solid sphere model -
J.J Thomson
He was the first to discover electrons. He believed that the atom was a sphere with positive charge and had electrons within it. He created the plum pudding model. -
Albert Einstein
He discovered that atoms do exist by using theories in quantum physics to explain the photoelectric effect. -
Robert Millikan
He was able to provide a value for the electric charge which was used in Niels Bohr's theoretical formula for the hydrogen spectrum. This was the first proof of Bohr's quantum theory of the atom.
Interesting fact: He is from Iowa. -
Ernest Rutherford
He created the nuclear model . He describe that the atom had a central positive nucleus surrounded by negative orbiting electrons. -
Niels Bohr
He was able to explain what happens inside an atom and developed a picture of the atomic structure (Planetary mode.) He recieved a noble prize for figuring out the structure of an atom. -
Louis De Broglie
His ideas were a basis for developing the wave mechanic theory. He recieved the noble Prize for physics on his wave nature of electron discovery in 1929. -
Wolfgang Pauli
He proposed a rule explaining the behavior of electrons in atoms (electrons orbit the nucleus of the atom.) The Pauli exclusion principle- no two electrons in an atom can have the same quantum number. -
Erwin Schrodinger
He combined the equations for the behavior of waves with the de Broglie equation to create a mathematical model for the distribution of electrons in an atom. -
Werner Heisenberg
He created the Uncertainty Principle- which assumes limits to the accuracy of knowledge about atomic behavior. -
James Chadwich
He discovered the neutron while working under Ernest Rutherford which solved the "Jigsaw puzzle" of the atom. He won a nobel prize in 1935. -
modern atomic model
This model consist of electrons that are in constant motion around the nucleus, while protrons and neutrons are in the nucleus. Within the protons and neutrons there are quarks moving.
