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300
Democritus 300 BC
philosopher who formulated an atomic theory for the universe -
Antoine Lavoisier
Discovery of the makeup of water, the discovery of combustion and resperation all as a function of oxygen. -
Law of Conservation of Mass
A fundamental principle of classical physics that matter cannot be created or destroyed in an isolated system. -
John Dalton
He is best known for his pioneering work in the development of modern atomic theory, and his research into colour blindness. -
Dalton's Atomic Theory
- All matter is made of atoms. Atoms are indivisible and indestructible.
- All atoms of a given element are identical in mass and properties
- Compounds are formed by a combination of two or more different kinds of atoms.
- A chemical reaction is a rearrangement of atoms.
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Dmitri Mendeleev
Was the developer of the periodic table. -
Cathode Ray Tube
Demonstrated the influence of a magnetic field to the
electron beam. The visible beam appears on the aluminum sheet covered with phosphor, will bent away from the center when a magnet is held near the tube. -
J.J Thomson
He discovered the electron in 1897. He received the Nobel Prize in Physics in 1906. -
Plum Pudding Atomic Model
J.J Thomson observed that electrons floating freely in an atom, much like negatively-charged plums surrounded by positively-charged pudding. -
Robert Millikan
Was an American experimental physicist honored with the Nobel Prize for Physics in 1923 for his measurement of the elementary electronic charge and for his work on the photoelectric effect. -
Rutherford Model
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Henry Moseley
developed the application of X-ray spectra to study atomic structure; Moseley's discoveries resulted in a more accurate positioning of elements in the Periodic Table by closer determination of atomic numbers. -
Bohr Planetary
The "planetary model" of the atom illustrated in the adjacent figure is used as a symbol for atomic energy . In the Bohr Model the neutrons and protons occupy a dense central region called the nucleus, and the electrons orbit the nucleus much like planets orbiting the Sun. -
Niels Bohr
came up with a revolutionary theory on atomic structures and radiation emission -
Gold Foil Experiment
The experiment was believed that the mass of an atom was spread evenly throughout the atom. However the experiment proved that there is instead a small, dense, positively charged nucleus surrounded by mostly empty space and very small, negatively charged electrons -
Erwin Schrodinger
In Niels Bohr's theory of the atom, the electrons absorb and emit radiation of fixed wavelengths when jumping between the fixed orbits around a nucleus. The theory gave a good description of the spectrum from the hydrogen atom, but must be further developed for more complicated atoms and molecules. -
Quantum Mechanical Model
model is based on mathematics. Although it is more difficult to understand than the Bohr model, it can be used to explain observations made on complex atoms. -
Ernest Rutherford
became known as the father of nuclear physics. He is considered the greatest experimentalist since Michael Faraday. -
James Chadwick
discovered the neutron -
Electron Cloud Model
an atom model wherein electrons are no longer depicted as particles moving around the nucleus in a fixed orbit
