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John Dalton FRS (/ ˈ d ɔː l t ən /; 6 September 1766 – 27 July 1844) was an English chemist, physicist and meteorologist. [1] He introduced the atomic theory into chemistry. He also researched colour blindness; as a result, the umbrella term for red-green congenital colour blindness disorders is Daltonism in several languages.
History of atomic theory. The current theoretical model of the atom involves a dense nucleus surrounded by a probabilistic "cloud" of electrons. Atomic theory is the scientific theory that matter is composed of particles called atoms. The definition of the word "atom" has changed over the years in response to scientific discoveries.
The Rutherford model was devised by Ernest Rutherford to describe an atom. Rutherford directed the Geiger–Marsden experiment in 1909, which suggested, upon Rutherford's 1911 analysis, that J. J. Thomson 's plum pudding model of the atom was incorrect. Rutherford's new model [1] for the atom, based on the experimental results, contained new ...
Plum pudding model. An atom with seven electrons arranged in a pentagonal dipyramid, as imagined by Thomson in 1905. The plum pudding model was the first scientific model of the atom to describe an internal structure. It was first proposed by J. J. Thomson in 1904 following his discovery of the electron in 1897, and was rendered obsolete by ...
In atomic physics, the Bohr model or Rutherford–Bohr model was the first successful model of the atom. Developed from 1911 to 1918 by Niels Bohr and building on Ernest Rutherford 's nuclear model, it supplanted the plum pudding model of J J Thomson only to be replaced by the quantum atomic model in the 1920s.
The earliest efforts to produce models of molecular structure was done by Project MAC using wire-frame models displayed on a cathode ray tube in the mid 1960s. In 1965, Carroll Johnson distributed the Oak Ridge thermal ellipsoid plot (ORTEP) that visualized molecules as a ball-and-stick model with lines representing the bonds between atoms and ...
The tube was evacuated to different amounts and a series of images recorded. At the lowest pressure the image of the open slit was clear, while images of the mica covered slit or the open slit at higher pressures were fuzzy. Rutherford explained these results as alpha-particle scattering [8]: 260 in a paper published in 1906. [35]
Diatomic molecules (from Greek di- 'two') are molecules composed of only two atoms, of the same or different chemical elements. If a diatomic molecule consists of two atoms of the same element, such as hydrogen (H2) or oxygen (O2), then it is said to be homonuclear. Otherwise, if a diatomic molecule consists of two different atoms, such as ...