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  2. History of atomic theory - Wikipedia

    en.wikipedia.org/wiki/History_of_atomic_theory

    Dalton thought that water was a "binary compound", i.e. one hydrogen atom and one oxygen atom. Dalton did not know that in their natural gaseous state, the ultimate particles of oxygen, nitrogen, and hydrogen exist in pairs (O 2, N 2, and H 2). Nor was he aware of valencies. These properties of atoms were discovered later in the 19th century.

  3. John Dalton - Wikipedia

    en.wikipedia.org/wiki/John_Dalton

    Various atoms and molecules as depicted in John Dalton's A New System of Chemical Philosophy (1808) Dalton published his first table of relative atomic weights containing six elements (hydrogen, oxygen, nitrogen, carbon, sulfur and phosphorus), relative to the weight of an atom of hydrogen conventionally taken as 1. [ 18 ]

  4. 1803 in science - Wikipedia

    en.wikipedia.org/wiki/1803_in_science

    September 3 – English scientist John Dalton starts using symbols to represent the atoms of different chemical elements. October 21 – John Dalton's atomic theory and list of molecular weights first made known, at a lecture in Manchester. [5] [6] William Hyde Wollaston discovers the chemical element rhodium.

  5. Law of multiple proportions - Wikipedia

    en.wikipedia.org/wiki/Law_of_multiple_proportions

    In reality, an ethylene molecule has two carbon atoms and four hydrogen atoms (C 2 H 4), and a methane molecule has one carbon atom and four hydrogen atoms (CH 4). In this particular case, Dalton was mistaken about the formulas of these compounds, and it wasn't his only mistake. But in other cases, he got their formulas right.

  6. 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 ...

  7. Timeline of atomic and subatomic physics - Wikipedia

    en.wikipedia.org/wiki/Timeline_of_atomic_and...

    1803 John Dalton introduces atomic ideas into chemistry and states that matter is composed of atoms of different weights; 1805 (approximate time) Thomas Young conducts the double-slit experiment with light; 1811 Amedeo Avogadro claims that equal volumes of gases should contain equal numbers of molecules

  8. Atomism - Wikipedia

    en.wikipedia.org/wiki/Atomism

    John Dalton. In 1808, English physicist John Dalton (1766–1844) assimilated the known experimental work of many people to summarize the empirical evidence on the composition of matter. [72] He noticed that distilled water everywhere analyzed to the same elements, hydrogen and oxygen. Similarly, other purified substances decomposed to the same ...

  9. Atom - Wikipedia

    en.wikipedia.org/wiki/Atom

    Various atoms and molecules from A New System of Chemical Philosophy (John Dalton 1808). In the early 1800s, John Dalton compiled experimental data gathered by him and other scientists and discovered a pattern now known as the "law of multiple proportions". He noticed that in any group of chemical compounds which all contain two particular ...