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John Dalton
John Dalton s theory says that all matter is composed by atoms, atoms cannot be made or destroyed, different elements have different type of atoms, also that reactions occure when atoms are rearranged, and that compounds are formed from atomos of the constituent element. -
Daltons Atomic Model
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William Crookes
William created a better vaccum pump to produce cathode-ray
tubes with a smaller residual gas pressure. He found out that cathode rays are negatively charged. -
William Crocks Atomic model
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J.J Thomson atomic model
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J.J Thomson
J:J Thomson discovered the electron studying electric discharge in a high-vacuum cathode-ray tube. Later in 1904 Thomson suggested a model of the atom as a sphere of positive matter in which electrons are positioned by electrostatic forces. -
Ernest Rutherford
Ernest theory is that the atom has a central postive nucleus surounded by negative orbiting electrons. The gold foil experiment "Involved the firing of radioactive particles through minutely thin metal foils (notably gold) and detecting them using screens coated with zinc sulfide (a scintillator)." said a scientist of Chemsoc Timeline. -
Rutherfords Model
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Neils Bohr
Neils assumed that electrons traveled in stationary orbits defined by their angular momentum. He also developed an explanation of atomic structure that contributed to the periodic table of elements. -
Bohrs Model
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James Chadwick
James predicted the atom would have a neutron. He also established that atomic number is determined by the numbers of protons in an atom. Famous for discovering neutron in atom. -
bibliography
-Brown, Andrew (1997). The Neutron and the Bomb: a Biography of Sir James Chadwick. Oxford [Oxfordshire]: Oxford University Press. ISBN 0-19-853992-4.
-"Niels Bohr Archive". Niels Bohr Archive. February 2002. Retrieved 2 March 2013.
-Bernard Pullman (1998) The Atom in the History of Human Thought, trans. by Axel Reisinger. Oxford Univ. Press.
Eric Scerri (2007) The Periodic Table, Its Story and Its Significance, Oxford University Press, New York.
