![]() Small doses of heavy water (a few grams in humans, containing an amount of deuterium comparable to that normally present in the body) are routinely used as harmless metabolic tracers in humans and animals. 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. Prokaryotic organisms, however, can survive and grow in pure heavy water (though they grow more slowly). Heavy water is slightly toxic in eukaryotic 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). 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).ĭeuterium 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). ĭeuterium 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. The physical properties of deuterium compounds can be different from the hydrogen analogs for example, D 2O is more viscous than H 2O. India is now probably the world's largest concentrator of heavy water, also used in nuclear power reactors. Canada uses heavy water as a neutron moderator for the operation of the CANDU reactor design. The world's leading "producer" of deuterium (technically, merely enricher or concentrator of deuterium) was Canada, until 1997 when the last plant was shut down (see more in the heavy water article). Thus, the existence of deuterium is one of the arguments in favor of the Big Bang theory over the steady state theory of the universe. This abundance seems to be a very similar fraction of hydrogen, wherever hydrogen is found. Stellar fusion destroys deuterium, and there are no known natural processes (for example, see the rare cluster decay), other than the Big Bang nucleosynthesis, which might have produced deuterium at anything close to the observed natural abundance of deuterium. The existence of deuterium on Earth, elsewhere in the solar system (as confirmed by planetary probes), and in the spectra of stars, is an important datum in cosmology. Natural abundanceĭeuterium 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 (HD or ¹H²H). The isotope weight ratios within other chemical elements are largely insignificant in this regard, explaining the lack of unique isotope symbols elsewhere. The reason deuterium has a distinct chemical symbol may be its large mass difference with protium (¹H) deuterium has a mass of 2.014 u, compared to the mean hydrogen atomic weight of 1.007947 u, and protium's mass of 1.007825 u. ![]() IUPAC allows both D and ²H, although ²H is preferred. Since it is an isotope of hydrogen with mass number 2, it is also represented by ²H. 6.3 "Heavy water" experiments in World War IIĭifferences between deuterium and common hydrogen (protium) Chemical symbolĭeuterium is frequently represented by the chemical symbol D.6.2 Deuterium predicted and finally detected.4.2 Approximated wavefunction of the deuteron.1 Differences between deuterium and common hydrogen (protium).The isotope name is formed from the Greek deuteros meaning "second", to denote the two particles comprising the nucleus. The nucleus of deuterium, called a deuteron, contains one proton and one neutron, whereas the far more common hydrogen nucleus contains no neutrons. However, it continues to persist in the outer solar atmosphere at roughly the same concentration as in Jupiter. There is little deuterium in the interior of the Sun, since thermonuclear reactions destroy it. Deuterium abundance on Jupiter is about 6 atoms in 10,000 (0.06% atom basis) these ratios presumably reflect the early solar nebula ratios, and those after the Big Bang. Deuterium thus accounts for approximately 0.015% (on a weight basis, 0.030%) of all naturally occurring hydrogen in the oceans on Earth (see VSMOW the abundance changes slightly from one kind of natural water to another). Deuterium, also called heavy hydrogen, is a stable isotope of hydrogen with a natural abundance in the oceans of Earth of approximately one atom in 6500 of hydrogen (~154 PPM).
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