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Democritus
Born in 460BC and Died in 370BC. All matter is composed of atoms, which are bits of matter too small to be seen. These atoms CANNOT be further split into smaller portions. -
Period: to
Where it all happened
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Antoine Lavoisier
belief that matter ;identified by weight, would be conserved through any reaction (the law of conservation of mass).Among his contributions to chemistry associated with this method were the understanding of combustion and respiration caused by chemical reactions with the part of the air. His definitive proof by composition and decomposition that water is made up of oxygen and hydrogen. -
John Dalton
Dalton found that there isnt anything smaller than atoms, and they make everything. He represented these by using wooden spheres. -
Max Planck
Originator of quantum theory. Came up with the Plank Constant: Relation with the energy of a phton and frequency electro magnetic wave. -
Marie Curie
She discovered that thorium also emitted radiation, and further, that the amount of radiation depended upon the amount of element present in the compound. Thus, she deduced that radioactivity does not depend on how atoms are arranged into molecules, but rather that it originates within the atoms themselves. This discovery is perhaps her most important scientific contribution -
Robert Millikan
His oil drop experiment helped to quantify the charge of an electron, which contributed greatly to our understanding of the structure of the atom and atomic theory. -
Ernest Rutherford
Observed that radioactive material took the same amount of time for half of it to decay. Discovered that there is a nucleus in an atom densely in the center with positve charges along with most of the atom's mass. Cancelling Thompson's pudding theory that the charges were spread evenly throughout the atom. created the planetary model of an atom. -
Albert Einstein
Provided powerful confirmation that atoms and molecules actually exist, through his analysis of Brownian motion. became the 20th century’s most famous scientist when the strange predictions he made in his General Theory of Relativity were verified by scientific observations. -
Niels Bohr
Created the Bohr model.Bohr hypothesized that electrons can move around the nucleus only at fixed distances from the nucleus based on the amount of energy they have. He called these fixed distances energy levels. Also said that energy is transferred only in certain well defined quantities. Electrons should move around the nucleus but only in prescribed orbits. -
J. J. Thomson
Discovered the electron in a series of experiments designed to study the nature of electric discharge in a high-vacuum cathode-ray tube.In 1904 Thomson suggested a model of the atom as a sphere of positive matter in which electrons are positioned by electrostatic forces.Thomson’s last important experimental program focused on determining the nature of positively charged particles. "plum pudding theory" -
Erwin Schrodinger
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James Chadwick
Chadwick bombarded beryllium atoms with alpha particles. An unknown radiation was produced. Chadwick interpreted this radiation as being composed of particles with a neutral electrical charge and the approximate mass of a proton. This particle became known as the neutron. -
Louis De Broglie
Best known for his research on quantum theory and for predicting the wave nature of electrons. -
Werner Heisenberg
We cannot, he said, always assign to an electron a position in space; He said this means that electrons do not travel in neat orbits. -
Jeremiah Creates Science Presentation.
Chemical Heritage Foundation." .Chemical Heritage Foundation. N.p., n.d. Web. 03 Feb. 2016.
Biographical." Scientist Biographical. NobelPrize.org, n.d. Web. 03 Feb. 2016.
"Atomic Theory." Atomic Heritage Foundation. N.p., n.d. Web. 04 Feb. 2016.
