-
democritus
His exact contributions are difficult to disentangle from those of his mentor Leucippus, as they are often mentioned together in texts. Their speculation on atoms, taken from Leucippus, bears a passing and partial resemblance to the nineteenth-century understanding of atomic structure that has led some to regard Democritus as more of a scientist than other Greek philosophers; however their ideas rested on very different bases. -
Antione Lavoisier
He named both oxygen (1778) and hydrogen(1783) and predicted silicon (1778). He helped construct the metric system, put together the first extensive list of elements, and helped to reform chemical nomenclature. -
John dalton
John Dalton was born into a Quaker family at Eaglesfield, near Cockermouth, Cumberland, England. He is best known for his pioneering work in the development of modern atomic theory, and his research into colour blindness -
J.J Thompson
Joseph John Thomson was born in 1856 in Cheetham Hill, Manchester, England. He is credited with discovering electrons and isotopes, and inventing the mass spectrometer. Thomson was awarded the 1906 Nobel Prize in Physics for the discovery of the electron and for his work on the conduction of electricity in gases. -
cathode tay tube
they were first observed in 1869 by German physicist Johann Hittorf, and were named in 1876 by Eugen Goldstein kathodenstrahlen, or cathode rays.[1] -
plum pudding model
The plum pudding model of the atom by J. J. Thomson, who discovered the electron in 1897, was proposed in 1904 before the discovery of the atomic nucleus in order to add the electron to the atomic model. In this model, the atom is composed of electrons. -
Robert milikan
obert A. Millikan (March 22, 1868 – December 19, 1953) was an American experimental physicist, and Nobel laureate in physics for his measurement of the charge on the electron and for his work on the photoelectric effect. -
Geiger-Marsden experiment
The Geiger–Marsden experiment experiment or the Rutherford was an experiment to probe the structure of the atom performed by Hans Geiger and Ernest Marsden in 1909 -
James chadwick
In 1932, Chadwick made a fundamental discovery in the domain of nuclear science: he proved the existence of neutrons - elementary particles devoid of any electrical charge. In contrast with the helium nuclei (alpha rays) which are charged, and therefore repelled by the considerable electrical forces present in the nuclei of heavy atoms, this new tool in atomic disintegration need not overcome any electric barrier and is capable of penetrating and splitting the nuclei of even the heaviest element -
erwin schrodinger
In autumn 1922 he analyzed the electron orbits in an atom from a geometric point of view, using methods developed by the mathematician Hermann Weyl. This work, in which it was shown that quantum orbits can be associated with certain geometric properties, was an important step in predicting some of the features of wave mechanics. -
niels bohr
Bohr developed the model of the atom with the nucleus at the center and electrons in orbit around it, which he compared to the planets orbiting the sun. He worked on the idea in quantum mechanics that electrons move from one energy level to another in discrete steps. -
bohr planetary model
he most important properties of atomic and molecular structure may be exemplified using a simplified picture of an atom that is called the Bohr Model. This model was proposed by Niels Bohr in 1915; it is not completely correct, but it has many features that are approximately correct and it is sufficient for much of our discussion. The correct theory of the atom is called quantum mechanics; the Bohr Model is an approximation to quantum mechanics that has the virtue of being much simpler.
