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hydrogen-2png
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deuterium
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2
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H or D
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1
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1
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0015%
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201355321270
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1+
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13135720
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0001
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2224573
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0002
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, also called '''heavy hydrogen''', is a
Stable Isotope of
Hydrogen with a
Natural Abundance in the oceans of one atom in 6400 of hydrogen (see
VSMOW ; the abundance changes slightly from one kind of natural water to another). The
Nucleus of deuterium, called a '''deuteron''', contains one
Proton and one
Neutron , whereas the far more common hydrogen nucleus consists only of a proton and no neutrons.
The
Chemical Symbol 2H identifies deuterium. The unofficial symbol D is also often used, even though deuterium is not a
Chemical Element in its own right.
Deuterium occurs in trace amounts naturally as deuterium gas, written
2H
2 or D
2, but most natural occurrence in the universe is bonded with a typical
1H atom, a gas called hydrogen deuteride.
1
The deuteron has spin +1 and is thus a
Boson . The NMR frequency of deuterium is significantly different from common light hydrogen. The two stable isotopes of hydrogen can be distinguished physically by using
Mass Spectrometry .
The physical properties of deuterium compounds can be different from the hydrogen analogs; for example, D
2O is more
Viscous than H
2O.
Deuterium behaves chemically similarly to ordinary hydrogen, but there are differences in bond energy and length for compounds of heavy hydrogen isotopes which are larger than the isotopic differences in any other element. Bonds involving deuterium and tritium are somewhat stronger than the corresponding bonds in light hydrogen, and these differences are enough to make significant changes in biological reactions (see
Heavy Water ).
Deuterium can replace the normal hydrogen in water molecules to form
Heavy Water (D
2O), which is about 10.6% more dense than normal water (enough that ice made from it sinks in ordinary water). Heavy water is modestly toxic in eukariotic animals, with 25% substitution of the body water causing cell division problems and sterility, and 50% substitution causing death by cytotoxic syndrome (bone marrow failure and gastrointestinal lining failure). Bacteria, however, can survive and grow in pure heavy water (though they grow more slowly). Consumption of heavy water would not pose a
Health Threat to humans unless very large quantities (in excess of 10 liters) were consumed over many days. Small doses of heavy water (a few grams) are routinely used as harmless metabolic tracers in humans and animals.
The existence of deuterium on Earth, elsewhere in the solar system (as confirmed by planetary probes), and in the spectra of
Star s, is an important datum in
Cosmology . Stellar fusion destroys deuterium, and there are no known natural processes, other than the
Big Bang Nucleosynthesis , which produce deuterium at anything close to the observed natural abundance of deuterium, which seems to be a very similar fraction wherever hydrogen is found. Thus, the existence of deuterium is one of the arguments in favour of the
Big Bang theory over the
Steady State Theory of the universe.
The world's leading "producer" of deuterium (technically, merely enricher or concentrator of deuterium) is
Canada , in the form of heavy water. Canada uses heavy water as
Neutron Moderator for the operation of the
CANDU Reactor design.
Deuterium is useful in
Nuclear Fusion reactions, especially in combination with
Tritium , because of the large reaction rate (or
Cross Section ) and high
Energy yield of the D-T reaction. Unlike
Protium , deuterium undergoes fusion purely via the strong interaction, making its use for commercial power plausible.
In
Chemistry and
Biochemistry , deuterium is used in
Tracer molecules to study
Chemical Reaction s and
Metabolic Pathway s, because chemically it behaves similarly to ordinary hydrogen, but it can be distinguished from ordinary hydrogen by its mass using
Mass Spectrometry .
Deuterium is particlarly useful in hydrogen nuclear magnetic resonance (1H-
NMR ). Because of deuterium's nuclear spin properties which differ from the hydrogen generally connected to molecules, NMR
Spectra of hydrogen/protium are highly differentiable from that of deuterium, and in practice are not "seen" by an NMR instrument tuned to light-hydrogen. Deuterated solvents are therefore routinely used in NMR specroscopy, in order to allow only the light-hydrogen spectra of the compound of interest to be measured.
Deuterium can also be used for femtosecond
IR spectroscopy, since the mass difference drastically affects the frequency of molecular vibrations; deuterium-carbon bond vibrations are found in locations free of other signals.
The existence of nonradioactive isotopes of lighter elements had been suspected in studies of neon as early as 1913, and proven by mass spectroscopy in 1920. The prevailing theory then, however, was that these were due to the existence of differing numbers of "nuclear electrons." It was expected that hydrogen, with a measured average atomic mass very close to 1 u, and a nucleus thought to be composed of a single proton (a known particle), could not contain nuclear electrons, and thus could have no heavy isotopes.
Deuterium was "predicted" in 1926 by
Walter Russell , using his "spiral" periodic table, and first detected in late 1931 by
Harold Urey , a chemist at
Columbia University . Urey distilled 5 liters of cryogenically-produced liquid hydrogen to 1 milliliter of liquid and showed spectroscopically that it contained a very small amount of isotope of hydrogen with an atomic mass of 2, and called the isotope "deuterium" from the Greek word for "two." The amount inferred for normal abundance was so small (only about 1 atom in 6400 hydrogen atoms in ocean water) that it had not noticably affected average hydrogen atomic mass. Urey was also able to concentrate water to show enrichment of this heavy isotope of hydrogen.
Gilbert Newton Lewis prepared the first pure samples of heavy water in 1933 (see
Heavy Water ). The discovery of deuterium, coming before the discovery of the neutron in 1932, was an experimental shock to theory, and after the neutron was reported, deuterium won Urey the Nobel Prize in chemistry in 1934.
For the history of
Heavy Water production, see that topic. During
World War II ,
Nazi Germany was known to be conducting experiments using heavy water as moderator for a
Nuclear Reactor design. This was a source of concern because it might allow them to produce
Plutonium for an
Atomic Bomb . Ultimately, it led to a seemingly important Allied operation, the
Norwegian Heavy Water Sabotage , to destroy the
Vemork deuterium production/enrichment facility in Norway. It turned out, however, that Germany was not putting any serious efforts into the program, and only had a small partly-built experimental reactor hidden away. At the end of the war, the Germans did not even have a fifth the amount of heavy water needed to run the reactor, partially due to the
Norwegian Heavy Water Sabotage operation. However, even had the Germans succeeded in getting a reactor operational (as America did with a graphite reactor in 1942), they would still have been at least several years away from development of an atomic bomb with maximal effort (the process required about 2 and a half years from first critical reactor to bomb, in both the U.S. and U.S.S.R).
- density: 0.180 kg/m3 at STP (0 °C, 101.325 kPa).
- atomic weight: 2.01355321270.
- mean abundance in ocean water (see VSMOW ) about 0.0156 %of H atoms = 1/6400 H atoms.
Data at approximately 18 K for D
2 (
Triple Point ):
- density:
- solid: 195 kg/m3
- gas: 0.452 kg/m3
- viscosity: 1.3 µPa·s
- specific heat capacity at constant pressure ''cp'':
- solid: 2950 J/(kg·K)
- gas: 5200 J/(kg·K)
An is the antiparticle of the nucleus of deuterium, consisting of an
Antiproton and an
Antineutron . The antideuteron was first produced at
CERN and the
Brookhaven National Laboratory in
1965 . A complete atom, with a
Positron orbiting the nucleus, would be called ''antideuterium'', but as of
2005 antideuterium has not yet been created. The symbol for antideuterium is the same as for deuterium, except with a bar over it.
