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John Dalton FRS (/ ˈ d ɔː l t ən /; 5 or 6 September 1766 – 27 July 1844) was an English chemist, physicist and meteorologist. [1] He introduced the atomic theory into chemistry.
In 1804, Dalton explained his atomic theory to his friend and fellow chemist Thomas Thomson, who published an explanation of Dalton's theory in his book A System of Chemistry in 1807. According to Thomson, Dalton's idea first occurred to him when experimenting with "olefiant gas" and "carburetted hydrogen gas" .
Modern atomic theory is not based on these old concepts. [2] [3] In the early 19th century, the scientist John Dalton noticed that chemical substances seemed to combine with each other by discrete and consistent units of weight, and he decided to use the word atom to refer to these units. [4]
The law of definite proportions contributed to the atomic theory that John Dalton promoted beginning in 1805, which explained matter as consisting of discrete atoms, that there was one type of atom for each element, and that the compounds were made of combinations of different types of atoms in fixed proportions. [5]
1803–1808 – John Dalton reconsiders the atomic theory of matter in order to understand chemistry. [22] 1816 – David Brewster discovers stress birefringence in diamond. [23] 1819 – Experimentally Pierre Louis Dulong and Alexis Thérèse Petit find that the specific heat capacity of solids was close to a constant value given by Dulong ...
John Dalton is remembered for his work on partial pressures in gases, color blindness, and atomic theory. Main articles: John Dalton and Atomic theory In 1803, English meteorologist and chemist John Dalton proposed Dalton's law , which describes the relationship between the components in a mixture of gases and the relative pressure each ...
During the 1920s, it was thought that the atomic nucleus was made of protons and electrons, which would account for the disparity between the atomic number of an atom and its atomic mass. [ 11 ] [ 12 ] In 1932, James Chadwick discovered an uncharged particle of approximately the mass as the proton, which he called the neutron . [ 13 ]
The term atomic physics can be associated with nuclear power and nuclear weapons, due to the synonymous use of atomic and nuclear in standard English. Physicists distinguish between atomic physics—which deals with the atom as a system consisting of a nucleus and electrons—and nuclear physics , which studies nuclear reactions and special ...