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  2. History of atomic theory - Wikipedia

    en.wikipedia.org/wiki/History_of_atomic_theory

    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]

  3. Law of multiple proportions - Wikipedia

    en.wikipedia.org/wiki/Law_of_multiple_proportions

    The discovery of this pattern led Dalton to develop the modern theory of atoms, as it suggested that the elements combine with each other in multiples of a basic quantity. Along with the law of definite proportions , the law of multiple proportions forms the basis of stoichiometry .

  4. John Dalton - Wikipedia

    en.wikipedia.org/wiki/John_Dalton

    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.

  5. History of molecular theory - Wikipedia

    en.wikipedia.org/wiki/History_of_molecular_theory

    John Dalton's union of atoms combined in ratios (1808) Similar to these views, in 1803 John Dalton took the atomic weight of hydrogen, the lightest element, as unity, and determined, for example, that the ratio for nitrous anhydride was 2 to 3 which gives the formula N 2 O 3. Dalton incorrectly imagined that atoms "hooked" together to form ...

  6. List of superseded scientific theories - Wikipedia

    en.wikipedia.org/wiki/List_of_superseded...

    John Dalton's model of the atom, which held that atoms are indivisible and indestructible (superseded by nuclear physics) and that all atoms of a given element are identical in mass (superseded by discovery of atomic isotopes). [13] Plum pudding model of the atom—assuming the protons and electrons were mixed together in a single mass

  7. History of the periodic table - Wikipedia

    en.wikipedia.org/wiki/History_of_the_periodic_table

    Dalton's 1806 list of known elements by atomic weight. In 1808–10, British natural philosopher John Dalton published a method by which to arrive at provisional atomic weights for the elements known in his day, from stoichiometric measurements and reasonable inferences. Dalton's atomic theory was adopted by many chemists during the 1810s and ...

  8. Atom - Wikipedia

    en.wikipedia.org/wiki/Atom

    But this ancient idea was based in philosophical reasoning rather than scientific reasoning. Modern atomic theory is not based on these old concepts. [2] [3] In the early 19th century, the scientist John Dalton found evidence that matter really is composed of discrete units, and so applied the word atom to those units. [4]

  9. Atomism - Wikipedia

    en.wikipedia.org/wiki/Atomism

    John Dalton's alternative formulae for water and ammonia. And then he proceeded to give a list of relative weights in the compositions of several common compounds, summarizing: [73] 1st. That water is a binary compound of hydrogen and oxygen, and the relative weights of the two elementary atoms are as 1:7, nearly; 2nd.