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  1. In chemical reactions, atoms are combined, separated, or rearranged. Dalton's atomic theory has been largely accepted by the scientific community, with the exception of three changes. We now know that (1) an atom can be further subdivided, (2) all atoms of an element are not identical in mass, and (3) using nuclear fission and fusion techniques ...

  2. Dalton’s atomic theory was a scientific theory on the nature of matter put forward by the English physicist and chemist John Dalton in the year 1808. It stated that all matter was made up of small, indivisible particles known as ‘atoms’. All substances, according to Dalton’s atomic theory, are made up of atoms, which are indivisible and ...

  3. Postulates of Dalton’s Atomic Theory. Dalton made a few assumptions in his atomic theory [1-4]. 1. All matter is composed of atoms that are indivisible. The laws of conservation of mass and definite proportions can be explained using the concept of atoms. Dalton proposed that all matter is made of tiny indivisible atoms, which he imagined as ...

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    John Dalton is best known for what became known as Dalton’s law, which posits that the total pressure of a gaseous mixture is equal to the sum of the partial pressures of the individual component gases, partial pressure being the pressure that each gas would exert alone within the volume of the mixture at the same temperature.

    Why was John Dalton so influential?

    John Dalton based his partial pressures theory on the idea that only like atoms repel one another, whereas unlike atoms appear to react indifferently. This notion was erroneous, but it helped to explain why each gas in a mixture behaved independently, serving the purpose of showing that atoms of all kinds are not alike.

    What were John Dalton’s other contributions to chemistry?

    John Dalton developed a crude method for measuring the masses of the elements in a compound. His law of multiple proportions states that when two elements form more than one compound, masses of one element that combine with a fixed mass of the other are in a ratio of small whole numbers.

    What were John Dalton’s other scientific contributions beyond chemistry?

    Dalton was born into a Quaker family of tradesmen; his grandfather Jonathan Dalton was a shoemaker, and his father, Joseph, was a weaver. Joseph married Deborah Greenup in 1755, herself from a prosperous local Quaker family. Dalton was the youngest of their three offspring who survived to adulthood. He attended John Fletcher’s Quaker grammar school in Eaglesfield. When John was only 12 years old, Fletcher turned the school over to John’s older brother, Jonathan, who called upon the younger Dalton to assist him with teaching. Two years later the brothers purchased a school in Kendal, where they taught approximately 60 students, some of them boarders.

    As a teacher, Dalton drew upon the experiences of two important mentors: Elihu Robinson, a Quaker gentleman of some means and scientific tastes in Eaglesfield, and John Gough, a mathematical and classical scholar in Kendal. From these men John acquired the rudiments of mathematics, Greek, and Latin. Robinson and Gough were also amateur meteorologists in the Lake District, and from them Dalton gained practical knowledge in the construction and use of meteorologic instruments as well as instruction in keeping daily weather records. Dalton retained an avid interest in meteorologic measurement for the rest of his life.

    In 1793 Dalton moved to Manchester to teach mathematics at a dissenting academy, the New College. He took with him the proof sheets of his first book, a collection of essays on meteorologic topics based on his own observations together with those of his friends John Gough and Peter Crosthwaite. This work, Meteorological Observations and Essays, was published in 1793. It created little stir at first but contained original ideas that, together with Dalton’s more developed articles, marked the transition of meteorology from a topic of general folklore to a serious scientific pursuit.

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    Born and reared in England’s mountainous Lake District, Dalton was well placed to observe various meteorologic phenomena. He upheld the view, against contemporary opinion, that the atmosphere was a physical mixture of approximately 80 percent nitrogen and 20 percent oxygen rather than being a specific compound of elements. He measured the capacity of the air to absorb water vapour and the variation of its partial pressure with temperature. He defined partial pressure in terms of a physical law whereby every constituent in a mixture of gases exerted the same pressure it would have if it had been the only gas present. One of Dalton’s contemporaries, the British scientist John Frederic Daniell, later hailed him as the “father of meteorology.”

    Soon after his arrival at Manchester, Dalton was elected a member of the Manchester Literary and Philosophical Society. His first contribution to this society was a description of the defect he had discovered in his own and his brother’s vision. This paper was the first publication on colour blindness, which for some time thereafter was known as Daltonism.

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    • Sydney Ross
  4. John Dalton - Atomic Theory, Chemistry, Physics: By far Dalton’s most influential work in chemistry was his atomic theory. Attempts to trace precisely how Dalton developed this theory have proved futile; even Dalton’s own recollections on the subject are incomplete. He based his theory of partial pressures on the idea that only like atoms in a mixture of gases repel one another, whereas ...

    • Sydney Ross
  5. 5 days ago · Dalton's atomic theory. A theory of chemical combination, first stated by John Dalton in 1803. It involves the following postulates: (1) Elements consist of indivisible small particles (atoms). (2) All atoms of the same element are identical; different elements have different types of atom. (3) Atoms can neither be created nor destroyed.

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  7. Dalton's Atomic Theory was formulated by John Dalton in 1808, and it remains a fundamental tenet of chemistry to this day. The five main points are: Matter is made up of atoms, small and indivisible particles. All atoms of the same element are identical and have the same mass. Atoms of different elements vary in size, mass, and chemical behavior.

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