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Period: 100 to
Atomic Models of Time
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400
400 B.C.E. Democritus's Atomic Model
Created theory of atoms and void; the universe is made up of empty space and a nearly infinite number or invisible particles differing in arrangement, form, and position. He stated that all all matter is composed of indivisible atoms. -
Period: to
Atomic Models
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Isaac Newton
Proposed a mechanical universe with small solid masses in motion. -
Lavoiser 1743-1794 Atomic Theory
Discovered water made of hydrogen and oxygen.
Dicovered Conservation of Mass. -
Dalton Atomic Theory
All matter is composed of atoms
Atoms cannot be made or destroyed
All atoms of the same element are identical
Different elements have different types of atoms
Chemical reactions occur when atoms are rearranged
Compounds are formed from atoms of the constituent elements. -
Thompson's Model
J.J. Thomson - 1898
First to measure the electron. Developed the plum-pudding model of the atom. Describes the atom as a slightly positive sphere with small electrons inside. -
Rutherford's Model
Ernest Rutherford - 1909-1911
Inferred a small, dense, positively-charged nucleus as the result of the alpha particle scattering gold foil experiment. -
Bohr Model
Neils Bohr - 1913 electrons could only orbit the nucleus in succesively larger orbits around the nucleus. The outer orbits could hold more electrons. The electrons in the outermost shell determine the properties of the atom. He also inferred that when an electron moves from an outer orbit to an inner orbit it emits a quantum of energy, a photon, in the form of light. -
Geiger
Geiger - 1925
Demonstrated that energy and mass are conserved in atomic processes. -
Erwin Schrodinger
Austrian Physicist- Comes from mathematical solutions. Determines the allowed energies an electron can have, and its various locations around the nucleus. -
Quantum Mechanical Model
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384-322 B.C.E. Aristostle
Provided basis of scientific work
