What is Deuterium?

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Hydrogen and Deuterium atomic structures

A stable isotope of hydrogen with a natural abundance in the oceans of Earth of approximately one atom in 6,400 of hydrogen (roughly 156.25 ppm) is known as Deuterium. It is also known as heavy hydrogen. Deuterium accounts for about 0.0156% of all naturally occurring hydrogen in the oceans on Earth. The nucleus of deuterium, called a deuteron, consists of one proton and one neutron, whereas the far more common hydrogen nucleus contains no neutron. The nucleus is the very dense region consisting of nucleons (protons and neutrons) at the center of an atom. The name of this isotope is derived from the Greek word “deuteros” meaning "second", to denote the two particles composing the nucleus.

 

Deuterium is non-radioactive, and is found in small quantities wherever hydrogen is present. Deuterium is chemically similar to regular hydrogen. Deuterium can replace the normal hydrogen in water molecules to form “Heavy water (D2O)”, which is about 10.6% more dense than normal water (enough that ice made from it sinks in ordinary water). Deuterium oxide, called “heavy water,” does show some strange effects due to deuterium's extra mass; it is thicker than regular water, and an ice cube of heavy water will sink. Organisms which consume small amounts of heavy water are generally unaffected, but the extra mass of deuterium causes a slight change in its bonding properties, and this can interrupt the biochemistry of a cell if too much heavy water is used. Deuterium is used as a tracer, in nuclear fusion reactors and to slow down neutrons in heavy water moderated fission reactors. Most organisms can be successfully grown on high levels of deuterium.

 

What is the History of Deuterium?

Deuterium was "predicted" in 1926 by Walter Russell, using his "spiral" periodic table, and first detected spectroscopically in late 1931 by Harold Urey, a chemist at Columbia University. Urey distilled five liters of cryogenically-produced liquid hydrogen to 1 mL of liquid and showed spectroscopically that it contained a very small amount of an isotope of hydrogen with an atomic mass of 2; Urey called the isotope "deuterium" from the Greek and Latin words for "two." The amount inferred for normal abundance of this heavy isotope was too tiny (only about 1 atom in 6400 hydrogen atoms in ocean water) that it had not noticeably affected previous measurements of (average) hydrogen atomic mass. Urey was also able to concentrate water to show partial enrichment of deuterium. The discovery of deuterium, which happened before the discovery of the neutron in 1932, was an experimental shock to theory, and after the discovery of neutron was reported, deuterium won Urey the Nobel Prize in chemistry in 1934.

 

Gilbert Newton Lewis, an American physicist prepared the first samples of pure heavy water in 1933. During World War II, Germany was known to be conducting experiments using heavy water as moderator for a nuclear reactor design. Such experiments were a source of concern because those experiments might allow Germans to produce plutonium for an atomic bomb. Eventually, it led to the operation called the "Norwegian heavy water sabotage", a series of actions undertaken by Norwegian saboteurs during World War II to prevent the German nuclear energy project from acquiring heavy water (deuterium oxide), which could be used to produce nuclear weapons. The purpose was to destroy the Vemork (name of a hydroelectric power plant) deuterium production/enrichment facility in Norway. At that time it was considered important to the potential progress of the war.

 

How does Deuterium occur in nature?

Deuterium occurs in trace amounts naturally as deuterium gas, written 2H2 or D2, but most natural occurrence in the universe is bonded with a typical 1H atom, a gas called hydrogen deuteride (HD or 1H2H). The natural deuterium abundance seems to be a very similar fraction of hydrogen, wherever hydrogen is found. The presence of deuterium is low but constant fraction in all hydrogen. It is estimated that the abundances of deuterium have not evolved significantly since their production about 13.7 billion years ago. The abundance of deuterium on Jupiter is about 2.25×10−5 (roughly 22 atoms in a million, or 15% of the terrestrial deuterium-to-hydrogen ratio). Yet, other sources suggest a much higher abundance of e.g., 6×10−4 (6 atoms in 10,000 or 0.06% atom basis). Deuterium is concentrated for industrial, scientific and military purposes as heavy water from ordinary water. The world's leading supplier of deuterium was Atomic Energy of Canada Limited, in Canada, until 1997 when the last plant was shut down.

 

What are the properties of Deuterium?

  • The chemical symbol of Deuterium is often depicted as D.
  • Since it is an isotope of hydrogen with atomic number 2, it is also represented by 2H.
  • It is thicker than regular water.
  • Chemically, deuterium behaves 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.
  • Deuterium can replace the normal hydrogen in water molecules to form heavy water (D2O), which is about 10.6% denser than normal water (enough that ice made from it sinks in ordinary water).
  • 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.

 

What are the Nuclear properties of the deuteron?

  • The nucleus of deuterium is called a ‘Deuteron’.
  • It has a mass of 2.013553212724(78) .
  • The charge radius of the deuteron is 2.1402(28) meter. The charge radius is a measure of the size of an atomic nucleus, particularly of a proton or a deuteron.
  • The proton and neutron making up deuterium can be dissociated (a general process in which ionic compounds (complexes or salts) separate or split into smaller particles, ions, usually in a reversible manner) through neutral current interactions with neutrinos. The cross section for this interaction is comparatively large, and deuterium was successfully used as a neutrino (meaning "small neutral one") target in the Sudbury Neutrino Observatory experiment in Canada. Neutral current interactions are one of the ways in which subatomic particles can interact by means of the weak force, one of the four fundamental forces of nature, alongside the strong nuclear force, electromagnetism, and gravity.
  • Due to the similarity in mass and nuclear properties between the proton and neutron, they are sometimes considered as two symmetric types of the same object, a nucleon. While only the proton has an electric charge, this is often negligible due of the weakness of the electromagnetic interaction relative to the strong nuclear interaction (force between two or more nucleons). The symmetry relating the proton and neutron is known as ‘isospin’ and denoted I (or sometimes T).
  • The Nuclear magnetic resonance (NMR) frequency of deuterium is significantly different from common light hydrogen. Nuclear magnetic resonance (NMR) is an effect whereby magnetic nuclei in a magnetic field absorb and re-emit electromagnetic (EM) energy.
  • Infrared spectroscopy also easily differentiates many deuterated compounds, due to the large difference in infra red absorption frequency seen in the vibration of a chemical bond containing deuterium, versus light hydrogen.

 

What are the Applications of Deuterium / Heavy Water?

  • Nuclear reactors: Deuterium is useful in nuclear fusion reactions, especially in combination with tritium (a radioactive isotope of hydrogen), because of the large reaction rate and high energy yield of the D–T reaction. Deuterium is used in heavy water moderated fission reactors, usually as liquid D2O, to slow neutrons without high neutron absorption of ordinary hydrogen. Heavy water reactors (HWR) are a class of fission reactor that uses heavy water as a neutron moderator.
  • NMR spectroscopy: Deuterium NMR spectra are especially informative in the solid state because of its relatively small quadrupole moment. A quadrupole or quadrapole is one of a sequence of configurations of — for example — electric charge or current, or gravitational mass that can exist in ideal form.
  • Tracing: In chemistry, biochemistry and environmental sciences, deuterium is used as a non-radioactive, stable isotopic tracer, for example, in the doubly labeled water test. Doubly labeled water is water in which both the hydrogen and the oxygen has been partly or completely replaced for tracing purposes.
  • Nuclear resonance spectroscopy: Deuterium is useful in hydrogen nuclear magnetic resonance spectroscopy. NMR ordinarily requires compounds of interest to be analyzed as dissolved in solution. Because of deuterium's nuclear spin properties which differ from the light hydrogen usually present in organic molecules, NMR spectra of hydrogen/protium are highly differentiable from that of deuterium, and in practice deuterium is not "seen" by an NMR instrument tuned to light-hydrogen.
  • Canada uses heavy water as a neutron moderator (medium that reduces the speed of fast neutrons) for the operation of the CANDU reactor, the CANada Deuterium Uranium reactor which is a Canadian-invented, pressurized heavy water reactor) design.
  • India is now probably the world's largest concentrator of heavy water, also used in nuclear power reactors
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