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  2. Hydrogen - Wikipedia

    en.wikipedia.org/wiki/Hydrogen

    Liquid hydrogen and liquid oxygen together serve as cryogenic propellants in liquid-propellant rockets, as in the Space Shuttle main engines. NASA has investigated the use of rocket propellant made from atomic hydrogen, boron or carbon that is frozen into solid molecular hydrogen particles suspended in liquid helium. Upon warming, the mixture ...

  3. Metallic hydrogen - Wikipedia

    en.wikipedia.org/wiki/Metallic_hydrogen

    The liquid hydrogen was in contact with wires leading to a device measuring electrical resistance. The scientists found that, as pressure rose to 140 GPa (1,400,000 atm; 21,000,000 psi), the electronic energy band gap, a measure of electrical resistance, fell to almost zero. The band gap of hydrogen in its uncompressed state is about 15 eV ...

  4. Heavy water - Wikipedia

    en.wikipedia.org/wiki/Heavy_water

    In the liquid state, a few water molecules are always in an ionized state, which means the hydrogen atoms can exchange among different oxygen atoms. Semi-heavy water could, in theory, be created via a chemical method, [ further explanation needed ] but it would rapidly transform into a dynamic mixture of 25% light water, 25% heavy water, and 50 ...

  5. Water - Wikipedia

    en.wikipedia.org/wiki/Water

    Tetrahedral structure of water. In a water molecule, the hydrogen atoms form a 104.5° angle with the oxygen atom. The hydrogen atoms are close to two corners of a tetrahedron centered on the oxygen. At the other two corners are lone pairs of valence electrons that do not participate in the bonding. In a perfect tetrahedron, the atoms would ...

  6. Hydrogen compounds - Wikipedia

    en.wikipedia.org/wiki/Hydrogen_compounds

    Water molecules have two hydrogen atoms and one oxygen atom. While H 2 is not very reactive under standard conditions, it does form compounds with most elements. Hydrogen can form compounds with elements that are more electronegative, such as halogens (F, Cl, Br, I), or oxygen; in these compounds hydrogen takes on a partial positive charge. [1]

  7. Liquid hydrogen - Wikipedia

    en.wikipedia.org/wiki/Liquid_hydrogen

    Liquid hydrogen also has a much higher specific energy than gasoline, natural gas, or diesel. [12] The density of liquid hydrogen is only 70.85 kg/m 3 (at 20 K), a relative density of just 0.07. Although the specific energy is more than twice that of other fuels, this gives it a remarkably low volumetric energy density, many fold lower.

  8. Deuterium-depleted water - Wikipedia

    en.wikipedia.org/wiki/Deuterium-depleted_water

    A nucleus of normal hydrogen (protium, 1 H) consists of one proton only, and no neutron. Deuterium thus has about twice the atomic mass as 1 H. Heavy water molecules contain two deuteriums instead of two 1 H atoms. The hydrogen in normal water is about 99.97% 1 H (by weight). [2]

  9. Chemical element - Wikipedia

    en.wikipedia.org/wiki/Chemical_element

    For example, molecules of water (H 2 O) contain atoms of hydrogen (H) and oxygen (O), so water can be said as a compound consisting of the elements hydrogen (H) and oxygen (O) even though it does not contain the chemical substances (di)hydrogen (H 2) and (di)oxygen (O 2), as H 2 O molecules are different from H 2 and O 2 molecules. For the ...