Hydrogen

Isotopes

Hydrogen is the only element that has different names for its isotopes.

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(During the early study of radioactivity, various heavy radioactive isotopes were given names, but such names are no longer used, although one element, radon, has a name that originally applied to only one of its isotopes.)

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The symbols D and T (instead of 2H and 3H) are sometimes used for deuterium and tritium, although this is not officially sanctioned. (The symbol P is already in use for phosphorus and is not available for protium.)

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;1H

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The most common isotope of hydrogen, this stable isotope has a nucleus consisting of a single proton; hence the descriptive, although rarely used, name protium. The spin of a protium atom is 1/2+. {{ref|ie.lbl.gov}}

Related Topics:
Nucleus - Proton - Protium - Spin

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;2H

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The other stable isotope is deuterium, with an extra neutron in the nucleus. Deuterium comprises 0.0184%–0.0082% of all hydrogen (IUPAC); ratios of deuterium to protium are reported relative to the VSMOW standard reference water. The spin of a deuterium atom is 1+.

Related Topics:
Deuterium - Neutron - IUPAC - VSMOW

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;3H

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The third naturally occurring hydrogen isotope is the radioactive tritium. The tritium nucleus contains two neutrons in addition to the proton. It decays through beta decay and has a half-life of 12.32 years. Tritium occurs naturally due to cosmic rays interacting with atmospheric gases. Like ordinary hydrogen, tritium reacts with the oxygen in the atmosphere to form T2O. This radioactive "water" molecule constantly enters the Earth's seas and lakes in the form of slightly radioactive rain, but its half-life is short enough to prevent a buildup of hazardous radioactivity. The spin of a tritium atom is 1/2+.

Related Topics:
Tritium - Beta decay - Years

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;4H

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Hydrogen-4 was synthesized by bombarding tritium with fast-moving deuterium nuclei. It decays through neutron emission and has a half-life of 9.93696x10-23 seconds. The spin of a hydrogen-4 atom is 2-.

Related Topics:
Hydrogen-4 - Neutron emission - Seconds

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;5H

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In 2001 scientists detected hydrogen-5 by bombarding a hydrogen target with heavy ions. It decays through neutron emission and has a half-life of 8.01930x10-23 seconds.

Related Topics:
Hydrogen-5 - Neutron emission - Seconds

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;6H

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Hydrogen-6 decays through triple neutron emission and has a half-life of 3.26500-22 seconds.

Related Topics:
Hydrogen-6 - Neutron emission - Seconds

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;7H

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In 2003 hydrogen-7 was created (article) at the RIKEN laboratory in Japan by colliding a high-energy beam of helium-8 atoms with a cryogenic hydrogen target and detecting tritons—the nuclei of tritium atoms—and neutrons from the break up of hydrogen-7, the same method used to produce and detect hydrogen-5.

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