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  2. Oxygen - Wikipedia

    en.wikipedia.org/wiki/Oxygen

    2 O) is an oxide of hydrogen and the most familiar oxygen compound. Hydrogen atoms are covalently bonded to oxygen in a water molecule but also have an additional attraction (about 23.3 kJ/mol per hydrogen atom) to an adjacent oxygen atom in a separate molecule. [127]

  3. Alternative approaches to redefining the kilogram - Wikipedia

    en.wikipedia.org/wiki/Alternative_approaches_to...

    The mole is currently defined as "the quantity of entities (elementary particles like atoms or molecules) equal to the number of atoms in 12 grams of carbon‑12". Thus, the current definition of the mole requires that ⁠ 1000 / 12 ⁠ moles ( ⁠83 + 1 / 3 ⁠ mol) of 12 C has a mass of precisely one kilogram.

  4. Ozone - Wikipedia

    en.wikipedia.org/wiki/Ozone

    The excess kinetic energy heats the stratosphere when the O atoms and the molecular oxygen fly apart and collide with other molecules. This conversion of UV light into kinetic energy warms the stratosphere. The oxygen atoms produced in the photolysis of ozone then react back with other oxygen molecule as in the previous step to form more ozone.

  5. Law of multiple proportions - Wikipedia

    en.wikipedia.org/wiki/Law_of_multiple_proportions

    [5] [6] Dalton described the "intermediate oxide" as being "2 atoms protoxide and 1 of oxygen", which adds up to two atoms of iron and three of oxygen. That averages to one and a half atoms of oxygen for every iron atom, putting it midway between a "protoxide" and a "deutoxide". [7] As with tin oxides, iron oxides are crystals. Example 3 ...

  6. Atom - Wikipedia

    en.wikipedia.org/wiki/Atom

    Adjusting these figures, in the black powder there is about 28 g of oxygen for every 100 g of iron, and in the red powder there is about 42 g of oxygen for every 100 g of iron. 28 and 42 form a ratio of 2:3. Dalton concluded that in these oxides, for every two atoms of iron, there are two or three atoms of oxygen respectively (Fe 2 O 2 and Fe 2 ...

  7. The first experiment to produce oxygen on another planet has ...

    www.aol.com/news/perseverance-rover-experiment...

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  8. Composition of the human body - Wikipedia

    en.wikipedia.org/wiki/Composition_of_the_human_body

    Water is ~11% hydrogen by mass but ~67% hydrogen by atomic percent, and these numbers along with the complementary % numbers for oxygen in water, are the largest contributors to overall mass and atomic composition figures. Because of water content, the human body contains more oxygen by mass than any other element, but more hydrogen by atom ...

  9. Mole (unit) - Wikipedia

    en.wikipedia.org/wiki/Mole_(unit)

    Before the 2019 revision of the SI, the mole was defined as the amount of substance of a system that contains as many elementary entities as there are atoms in 12 grams of carbon-12 (the most common isotope of carbon). [19] The term gram-molecule was formerly used to mean one mole of molecules, and gram-atom for one mole of atoms. [15]