Deuterium

• Deuterium
• Diplogen (deprecated)

Colorless and odorless gas

Gaseous

0.17 kg · m-3

-254.43 ° C

-249.58 ° C

Risk

Template: Infobox chemical / molecular formula search available

Deuterium (from Greek δεύτερος deuteros, the Second ' ) is a natural isotope of hydrogen. Its nucleus is also called deuteron, it consists of one proton and one neutron (2H ). Deuterium is called because of its mass as " Heavy Hydrogen". It was discovered in 1931 by the American chemist Harold C. Urey. He was awarded the 1934 Nobel Prize in Chemistry.

The other two isotopes of hydrogen are protium (1 H) and tritium ( 3H).

Independent names and symbols for isotopes of an element is unique to deuterium (symbol D instead 2H) and tritium ( T symbol instead 3H), because the mass ratio between protium and its isotopes is relatively large (deuterium and tritium 1:2 1:3 ) and this results in significant differences in the chemical behavior. ( In comparison, the next largest isotopes 3He and 4He pair are 1:1,33; 235U and 238U at only 1:1,013 ).

Description

The chemical symbol is 2H; For reasons of simplicity, in the formula and D notation is often used.

In contrast to 1H is hydrogen, whose nucleus consists of only one proton, the deuterium core includes a neutron in addition to this proton. The amount of deuterium in naturally occurring hydrogen is 0.015 %.

It is assumed that deuterium has arisen only in the primordial nucleosynthesis immediately after the Big Bang, because the deuterium formed in the stellar nucleosynthesis merged after a short period to continue to helium. Therefore, the frequency of the deuterium in the universe is an important parameter for cosmological models.

As normal hydrogen is deuterium only in bound form. In the simplest case, two deuterium atoms combine to form deuterium molecule. There are, depending on the total spin IG of the molecule two variants, the ortho deuterium (o- D2 ) when the Kernspinisomer the total spin 0 and 2 has, and the deuterium para (p- D2) in the case of G = I 1

Occurrence

The natural abundance of the isotope D is 0.015 % of H. The occurring on Earth water ( 1.4 billion cubic kilometers, or 1.4 x 1018 t) consists of approx. ninth ( 2 of 18 u) or approx. 11.1% of hydrogen (including deuterium), therefore it contains 0.000018 %, or 2.5 x 1013 t deuterium.

Extraction

Deuterium is easier to accumulate than the isotopes of other elements such as uranium, due to the large relative mass difference. In the first enrichment step is usually the Girdler sulfide process used. This makes use of that in an aqueous hydrogen sulfide solution, the hydrogen atoms and deuterium atoms exchange places between the two types of molecules: at low temperatures, the Deuterium migrates preferentially in the water molecule, at high temperatures in the hydrogen sulfide molecule. In the final enrichment stage, the mixture of H2O, HDO and D2O is separated by distillation.

Applications

Deuterium is used as a moderator in nuclear reactors ( here in the form of heavy water ). , As fuel in hydrogen bombs, as a substitute for protium ( ordinary hydrogen) in solvents for 1H - NMR spectroscopy and used as a tracer in chemistry and biology There is also in NMR spectroscopy (in particular, the solid-state NMR ) is an important isotope label to detect the dynamics of organic matter and to elucidate structures. Further gaseous deuterium is used in special lamps in photometers, for example in the atomic spectroscopy source of UV light.

Heavy water

If you replace the water ( H2O) to hydrogen by deuterium, we obtain heavy water ( D2O ). In mixtures is due to the rapid exchange of protons and deuterons statistically also " semi- heavy" water ( HDO) ago.

The density of D 2 O is 1.1047 gcm -3 at 25 ° C, the melting point is 3.8 ° C and the boiling point of 101.4 ° C. The density maximum is 11.2 ° C (water: 3.98 ° C). These differences in physical properties with respect to water is called isotope effect. He is most pronounced among all nuclides between 1H and 2H.

Heavy water slows or prevents many metabolic processes, which is why most organisms are only limited at very high deuterium content viable.

• Heavy water has a reduced ability to solve compared to normal water.
• Deuterons have a lower tunnel assets as protons and therefore difficult in biological systems, the maintenance of the electrochemical gradient in mitochondrial membranes. But they are crucial for the synthesis of ATP.
• The functionality of the majority of proteins is dependent on the mobility of the surrounding water molecules. Since deuterons are carriers because of the larger mass, the proteins can no longer perform their duties only get worse or at all.

Safety

Deuterium (formerly Directive 67/548/EEC ) in the GHS is not listed, but is to be regarded in this respect as hydrogen, since all isotopes of an element with respect to their chemical behavior and its harmfulness are very similar.