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  2. Hydrogen - Wikipedia

    en.wikipedia.org/wiki/Hydrogen

    Hydrogen is found in great abundance in stars and gas giant planets. Molecular clouds of H 2 are associated with star formation. Hydrogen plays a vital role in powering stars through the proton-proton reaction in case of stars with very low to approximately 1 mass of the Sun and the CNO cycle of nuclear fusion in case of stars more massive than ...

  3. Densities of the elements (data page) - Wikipedia

    en.wikipedia.org/wiki/Densities_of_the_elements...

    1 H hydrogen (H 2) use: 0.08988 g/L: 0 °C, 101.325 kPa ... 1.696 g/L: 1.6074 kg/m 3: 15 °C, 1.013 bar ... formula weight = 222 Notes

  4. Energy density - Wikipedia

    en.wikipedia.org/wiki/Energy_density

    The hydrogen may be around 5.7% of the total mass, [22] giving just 6.8 MJ per kg total mass for the LHV. See note above about use in fuel cells. Hydrogen, gas (1 atm or 101.3 kPa, 25 °C)

  5. Hydrogen atom - Wikipedia

    en.wikipedia.org/wiki/Hydrogen_atom

    A hydrogen atom is an atom of the chemical element hydrogen. The electrically neutral hydrogen atom contains a single positively charged proton in the nucleus, and a single negatively charged electron bound to the nucleus by the Coulomb force. Atomic hydrogen constitutes about 75% of the baryonic mass of the universe. [1]

  6. Atomic mass - Wikipedia

    en.wikipedia.org/wiki/Atomic_mass

    The atomic mass (relative isotopic mass) is defined as the mass of a single atom, which can only be one isotope (nuclide) at a time, and is not an abundance-weighted average, as in the case of relative atomic mass/atomic weight. The atomic mass or relative isotopic mass of each isotope and nuclide of a chemical element is, therefore, a number ...

  7. Molar mass - Wikipedia

    en.wikipedia.org/wiki/Molar_mass

    The molar mass of atoms of an element is given by the relative atomic mass of the element multiplied by the molar mass constant, M u ≈ 1.000 000 × 10 −3 kg/mol ≈ 1 g/mol. For normal samples from Earth with typical isotope composition, the atomic weight can be approximated by the standard atomic weight [ 2 ] or the conventional atomic weight.

  8. Energy density Extended Reference Table - Wikipedia

    en.wikipedia.org/wiki/Energy_density_Extended...

    Metallic hydrogen (recombination energy) 216 [2] Specific orbital energy of Low Earth orbit (approximate) 33.0: Beryllium + Oxygen: 23.9 [3] Lithium + Fluorine: 23.75 [citation needed] Octaazacubane potential explosive: 22.9 [4] Hydrogen + Oxygen: 13.4 [5] Gasoline + Oxygen –> Derived from Gasoline: 13.3 [citation needed] Dinitroacetylene ...

  9. Liquid hydrogen - Wikipedia

    en.wikipedia.org/wiki/Liquid_hydrogen

    Liquid hydrogen (H 2 (l)) is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecular H 2 form. [4] To exist as a liquid, H 2 must be cooled below its critical point of 33 K. However, for it to be in a fully liquid state at atmospheric pressure, H 2 needs to be cooled to 20.28 K (−252.87 °C; −423.17 °F). [5]