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In situ availability: trace
Necessity: critical
Atomic number: 1
Atomic mass: 1.00794
group: 1
period: 1
normal phase: Gas
series: Non-metals
density: 0.08988 g/L
melting point: 14.175K
boiling point: 20.418K
N/A ← H → He
Atomic radius (pm): 25
Bohr radius (pm): 53
Covalent radius (pm): 37
Van der Waals radius (pm): 120
ionic radius (pm): -
1st ion potential (eV): 13.60
Electron Configuration
Electrons Per Shell
Electronegativity: 2.2
Electron Affinity:
Oxidation states: 1
Crystal structure: Hexagonal


Hydrogen is a Non-metal in group 1. It has a Hexagonal crystalline structure. This element has two stable isotopes: 1 and 2.

Natural Isotopes

  • 1H (single electron, single proton)
  • 2H Deuterium (single electron, single proton, single neutron)

Synthetic Isotopes

  • 3H Tritium (single electron, single proton, two neutrons)
    • 12.33 year half life. Undergoes Beta Decay to become Helium 3(He3 or 3He)
  • 4H
    • Undergoes immediate Neutron Decay to become Tritium(3H)

Hydrogen is the simplest, lightest, and first element formed after the big bang. It is the most common element, making up approx 90% of the universe by weight.

Applications to Lunar Colonization

Hydrogen has many proposed applications in a lunar environment. These include rocket fuel, energy storage, reduction of metal and carbon oxides, and many other uses. Hydrogen production and recycling could become major functions of a lunar outpost.

Deuterium could be used as fuel in nuclear fusion reactions, although the percentage of deuterium in lunar hydrogen is significantly less than on earth, which could make its production difficult.

Lunar Hydrogen Production

The moon is significantly depleted of hydrogen compared to the earth. On earth, hydrogen is most commonly found combined with oxygen in the form of water (H2O). The Moon is much smaller than Earth, and its gravity is not strong enough to retain a gaseous atmosphere permanently. In addition, the moon lacks a magnetic field, allowing the solar wind to directly interact with its surface, constantly stripping away any atmosphere it manages to cling to. As a result, most of the volatiles of the Moon, including hydrogen, have long since evaporated and escaped into space.

However, hydrogen is constantly implanted into the lunar surface by the same solar wind that strips it away. As such, hydrogen is found in the lunar regolith in concentrations in the range of 40-50 parts per million. Methods of extracting hydrogen (along with other deposited volatiles) from the lunar surface have been proposed, usually involving heating the regolith until outgassing occurs (see Volatiles).

In addition, more concentrated reserves of hydrogen exist in deep craters at the Lunar poles in the form of water ice. These craters are permanently shielded from the sun, and as such are quite cold (< 100 K). These areas act as cold traps for any volatiles that happen to pass into them, whether from comet impact or ongoing creation via the solar wind. As a result, they contain significant amounts of water, as well as other volatiles.

Mining these polar deposits poses the problem of designing equipment capable of operating in extremely cold temperatures. In addition, the exact amount of resources available in these craters is not known, being a subject of some debate.

Related Pages

External Links

Environmental Chemistry: Hydrogen
WebElements: Hydrogen