Helium

Helium is the second most abundant and second lightest element in the universe, and is one of the elements believed to have been created in the Big Bang. In the modern universe almost all new helium is created as a result of the fractional distillation.

In 1868 the French astronomer silicon wafers).

Notable characteristics

Gas and plasma phases

Helium is the least reactive member of the solids is three times that of air and around 65% that of hydrogen.^[1]

Helium is less water K at 1 atmosphere) does it cool upon free expansion. Once precooled below this temperature, helium can be liquefied through expansion cooling.

Throughout the universe, helium is found mostly in a aurora.

Solid and liquid phases

Main article: Liquid helium

Helium solidifies only under great pressure. The resulting colorless, almost invisible crystalline structure.

Solid helium has a density of 0.214 ±0.006 g/ml (1.15 K, 66 atm) with a mean isothermal compressibility of the solid at 1.15 K between the solidus and 66 atm of 0.0031 ±0.0008/atm. Also, no difference in density was noted between 1.8 K and 1.5 K. This data projects that T=0 solid helium under 25 bar of pressure (the minimum required to freeze helium) has a density of 0.187 ±0.009 g/ml.^[5]

Helium I state

Below its lambda point, when it stops boiling and suddenly expands. The rate of expansion decreases below the lambda point until about 1 K is reached; at which point expansion completely stops and helium I starts to contract again.

Helium I has a gas-like heat) from masking the atomic properties.^[6]

Helium II state

Liquid helium below its lambda point begins to exhibit very unusual characteristics, in a state called helium II. Boiling of helium II is not possible due to its high superfluid phase, but only at much lower temperatures; as a result, less is known about such properties in the isotope helium-3.

Helium II is a viscosity. However, when measurements were done between two moving discs, a viscosity comparable to that of gaseous helium was observed. Current theory explains this using the two-fluid model for helium II. In this model, liquid helium below the lambda point is viewed as containing a proportion of helium atoms in a ground state, which are superfluid and flow with exactly zero viscosity, and a proportion of helium atoms in an excited state, which behave more like an ordinary fluid.^[7]

Helium II also exhibits a "creeping" effect. When a surface extends past the level of helium II, the helium II moves along the surface, seemingly against the force of gravity. Helium II will escape from a vessel that is not sealed by creeping along the sides until it reaches a warmer region where it evaporates. It moves in a 30 nm-thick film regardless of surface material. This film is called a Van der Waals force.^[10] These waves are known as third sound.

In the fountain effect, a chamber is constructed which is connected to a reservoir of helium II by a sintered disc through which superfluid helium leaks easily but through which non-superfluid helium cannot pass. If the interior of the container is heated, the superfluid helium changes to non-superfluid helium. In order to maintain the equilibrium fraction of superfluid helium, superfluid helium leaks through and increases the pressure, causing liquid to fountain out of the container.^[11]

The thermal conductivity of helium II is greater than that of any other known substance, a million times that of helium I and several hundred times that of second sound.^[8]

Applications

Helium is used for many purposes that require some of its unique properties, such as its low inertness. Helium is commercially available in either liquid or gaseous form. As a liquid, it can be supplied in small containers called dewars which hold up to 1,000 liters of helium, or in large ISO containers which have nominal capacities as large as 11,000 gallons (41,637 liters). In gaseous form, small quantities of helium are supplied in high pressure cylinders holding up to 300 standard cubic feet, while large quantities of high pressure gas are supplied in tube trailers which have capacities of up to 180,000 standard cubic feet.

Because it is calculation.)

For its low solubility in water, the major part of human blood, air mixtures of helium with oxygen toxicity.

At extremely low temperatures, liquid helium is used to cool certain metals to produce cryogenics.

For its inertness and high neutron transparency, and because it does not form radioactive isotopes under reactor conditions, helium is used as a coolant in some nuclear reactors, such as pebble-bed reactors.

Helium is used as a shielding gas in arc welding processes on materials that are contaminated easily by air. It is especially useful in overhead welding, because it is lighter than air and thus floats, whereas other shielding gases sink.

Because it is inert, helium is used as a protective gas in growing zirconium production, in gas chromatography, and as an atmosphere for protecting historical documents. This property also makes it useful in supersonic wind tunnels.

In rocketry, helium is used as an ullage medium to displace fuel and oxidizers in storage tanks and to condense rocket fuel. It is also used to purge fuel and oxidizer from ground support equipment prior to launch and to pre-cool liquid hydrogen in space vehicles. For example, the Saturn V booster used in the Apollo program needed about 13 million cubic feet (370,000 m³) of helium to launch.^[2]

The neon.

Because it diffuses through solids at a rate three times that of air, helium is used as a tracer gas to detect leaks in high-vacuum equipment and high-pressure containers, as well as in other applications with less stringent requirements such as heat exchangers, valves, gas panels, etc.

Because of its extremely low index of refraction, the use of helium reduces the distorting effects of temperature variations in the space between lenses in some telescopes.

The age of helium dating.

The high thermal conductivity and sound velocity of helium is also desirable in thermoacoustic refrigeration. The inertness of helium adds to the environmental advantage of this technology over conventional refrigeration systems which may contribute to ozone depleting and global warming effects.

Because helium alone is less dense than atmospheric air, it will change the timbre (not pitch^[12]) of a person's voice when inhaled. However, inhaling it from a typical commercial source, such as that used to fill balloons, can be dangerous due to the risk of asphyxiation from lack of oxygen, and the number of contaminants that may be present. These could include trace amounts of other gases, in addition to aerosolized lubricating oil.

History

Scientific discoveries

Evidence of helium was first detected on August 18, 1868 as a bright yellow line with a wavelength of 587.49 nanometres in the Edward Frankland named the element with the Greek word for the Sun, ἥλιος (helios)^[14]

On 26 March 1895 British chemist atomic weight.^[19] Helium was also isolated by the American geochemist William Francis Hillebrand prior to Ramsay's discovery when he noticed unusual spectral lines while testing a sample of the mineral uraninite. Hillebrand, however, attributed the lines to nitrogen. His letter of congratulations to Ramsay offers an interesting case of discovery and near-discovery in science.^[20]

In 1907, triple point temperature where the solid, liquid, and gas phases are at equilibrium. It was first solidified in 1926 by his student Willem Hendrik Keesom by subjecting helium to 25 atmospheres of pressure.

In 1938, Russian physicist Pyotr Leonidovich Kapitsa discovered that superfluidity. In 1972, the same phenomenon was observed in helium-3 by American physicists Douglas D. Osheroff, David M. Lee, and Robert C. Richardson.

History of extraction and use

After an oil drilling operation in 1903 in Dexter, Kansas, U.S. produced a gas geyser that would not burn, Kansas state geologist Erasmus Haworth collected samples of the escaping gas and took them back to the University of Kansas at Lawrence where, with the help of chemists Hamilton Cady and David McFarland, he discovered that the gas contained, by volume, 72% nitrogen, 15% methane—insufficient to make the gas combustible, 1% hydrogen, and 12% of an unidentifiable gas.^[21] With further analysis, Cady and McFarland discovered that 1.84% of the gas sample was helium.^[22] Far from being a rare element, helium was present in vast quantities under the American Great Plains, available for extraction from natural gas.

This put the United States in an excellent position to become the world's leading supplier of helium. Following a suggestion by Sir Richard Threlfall, the United States Navy sponsored three small experimental helium production plants during World War I. The goal was to supply barrage balloons with the non-flammable lifting gas. A total of 200,000 cubic feet (5700 m³) of 92% helium was produced in the program even though only a few cubic feet (less than 100 liters) of the gas had previously been obtained.^[15] Some of this gas was used in the world's first helium-filled airship, the U.S. Navy's C-7, which flew its maiden voyage from Hampton Roads, Virginia to Bolling Field in Washington, D.C. on 1 December 1921.^[23]

Although the extraction process, using low-temperature gas liquefaction, was not developed in time to be significant during World War I, production continued. Helium was primarily used as a lifting gas in lighter-than-air craft. This use increased demand during World War II, as well as demands for shielded arc welding. Helium was also vital in the atomic bomb Manhattan Project.

The government of the United States set up the National Helium Reserve in 1925 at Amarillo, Texas with the goal of supplying military airships in time of war and commercial airships in peacetime. Due to a US military embargo against Germany that restricted helium supplies, the Hindenburg was forced to use rocket fuel (among other uses) during the Space Race and Cold War. Helium use in the United States in 1965 was more than eight times the peak wartime consumption.

After the "Helium Acts Amendments of 1960" (Public Law 86–777), the U.S. Bureau of Mines arranged for five private plants to recover helium from natural gas. For this helium conservation program, the Bureau built a 425-mile (684 km) pipeline from Bushton, Kansas to connect those plants with the government's partially depleted Cliffside gas field, near Amarillo, Texas. This helium-nitrogen mixture was injected and stored in the Cliffside gas field until needed, when it then was further purified.

By 1995, a billion cubic metres of the gas had been collected and the reserve was US$1.4 billion in debt, prompting the Congress of the United States in 1996 to phase out the reserve.^[21]^[24] The resulting "Helium Privatization Act of 1996"^[25] (Public Law 104–273) directed the United States Department of the Interior to start liquidating the reserve by 2005.^[26]

Helium produced before 1945 was about 98% pure (2% nitrogen), which was adequate for airships. In 1945 a small amount of 99.9% helium was produced for welding use. By 1949 commercial quantities of Grade A 99.995% helium were available.

For many years the United States produced over 90% of commercially usable helium in the world. Extraction plants created in Canada, Poland, Russia, and other nations produced the remaining helium. In the mid 1990s, A new plant in Arzew, Algeria producing 600mmcf came on stream, with enough production to cover all of Europe's demand. Subsequently, in 2004–2006 two additional plants, one in Ras Laffen, Qatar and the other in Skikda, Algeria were built, but as of early 2007, Ras Laffen is functioning at 50%, and Skikda has yet to start up. Algeria quickly became the second leading producer of helium. Through this time, both helium consumption and the costs of producing helium increased and during 2007 the major suppliers, Air Liquide, Airgas and Praxair all raised prices from 10 to 30%.

Occurrence and production

Natural abundance

Helium is the second most abundant element in the known Universe after CNO cycle. According to the Big Bang model of the early development of the universe, the vast majority of helium was formed during Big Bang nucleosynthesis, from one to three minutes after the Big Bang. As such, measurements of its abundance contribute to cosmological models.

In the Earth's atmosphere, the concentration of helium by volume is only 5.2 parts per million.^[27] The concentration is low and fairly constant despite the continuous production of new helium because most helium in the Earth's atmosphere escapes into space by several processes.^[28]^[29] In the Earth's heterosphere, a part of the upper atmosphere, helium and other lighter gases are the most abundant elements.

Nearly all helium on Earth is a result of volcanic gas, and meteoric iron. The greatest concentrations on the planet are in natural gas, from which most commercial helium is derived.

Modern extraction

For large-scale use, helium is extracted by cryogenic process. This is necessary for applications requiring liquid helium and also allows helium suppliers to reduce the cost of long distance transportation, as the largest liquid helium containers have more than five times the capacity of the largest gaseous helium tube trailers.

In 2005, approximately one hundred and sixty million cubic meters of helium were extracted from natural gas or withdrawn from helium reserves, with approximately 83% from the United States, 11% from Algeria, and most of the remainder from Russia and Poland. In the United States, most helium is extracted from natural gas in Kansas and Texas.

Diffusion of crude natural gas through special semipermeable membranes and other barriers is another method to recover and purify helium. Helium can be synthesized by bombardment of protons, but this is not an economically viable method of production.

Isotopes

Main article: Isotopes of helium

Although there are eight known stable. In the Earth's atmosphere, there is one He-3 atom for every million He-4 atoms.^[32] However, helium is unusual in that its isotopic abundance varies greatly depending on its origin. In the interstellar medium, the proportion of He-3 is around a hundred times higher.^[33] Rocks from the Earth's crust have isotope ratios varying by as much as a factor of ten; this is used in geology to study the origin of such rocks.

The most common isotope, helium-4, is produced on Earth by nucleons are arranged into complete shells. It was also formed in enormous quantities during Big Bang nucleosynthesis.

solar winds.

The different formation processes of the two stable isotopes of helium produce the differing isotope abundances. These differing isotope abundances can be used to investigate the origin of rocks and the composition of the Earth's mantle.^[35]

It is possible to produce exotic helium isotopes, which rapidly decay into other substances. The shortest-lived heavy helium isotope is helium-5 with a gamma ray. Helium-7 and helium-8 are hyperfragments that are created in certain nuclear reactions.^[37]

The exotics helium-6 and helium-8 are known to exhibit a nuclear halo. Helium-2 (two protons, no neutrons) is a half-life of 3x10⁻²⁷ second.^[38]

Biological effects

The voice of a person who has inhaled helium temporarily sounds high-pitched. This is because the sulfur hexafluoride)

Inhaling helium, e.g. to produce the vocal effect, can be dangerous if done to excess since helium is a simple asphyxiant, thus it displaces carbon dioxide rather than lack of oxygen, so asphyxiation by helium progresses without the victim experiencing air hunger. Inhaling helium directly from pressurized cylinders is extremely dangerous as the high flow rate can result in barotrauma, fatally rupturing lung tissue.^[39]

Neutral helium at standard conditions is non-toxic, plays no biological role and is found in trace amounts in human blood. At high pressures, a mixture of helium and oxygen (heliox) can lead to high pressure nervous syndrome; however, increasing the proportion of nitrogen can alleviate the problem.^[40]

Containers of helium gas at 5 to 10 K should be handled as if they contain liquid helium due to the rapid and significant room temperature.^[2]

Compounds

Helium is chemically unreactive under all normal conditions due to its HArF, discovered in 2000.

Helium has been put inside the hollow carbon cage molecules (the fullerenes) by heating under high pressure of the gas. The neutral molecules formed are stable up to high temperatures. When chemical derivatives of these fullerenes are formed, the helium stays inside. If helium-3 is used, it can be readily observed by helium NMR spectroscopy. Many fullerenes containing helium-3 have been reported. These substances fit the definition of compounds in the Handbook of Chemistry and Physics. They are the first stable neutral helium compounds to be formed.

References

Prose

The Elements: Third Edition, by John Emsley (New York; Oxford University Press; 1998; pages 94–95) ISBN 0-19-855818-X
United States Geological Survey (usgs.gov): Mineral Information for Helium (PDF) (viewed 5 January 2007)
The thermosphere: a part of the heterosphere, by J. Vercheval (viewed 1 April 2005)
Isotopic Composition and Abundance of Interstellar Neutral Helium Based on Direct Measurements, Zastenker G.N. et al., [1], published in Astrophysics, April 2002, vol. 45, no. 2, pp. 131–142(12)
Dynamic and thermodynamic properties of solid helium in the reduced all-neighbours approximation of the self-consistent phonon theory, C. Malinowska-Adamska, P. Sŀoma, J. Tomaszewski, physica status solidi (b), Volume 240, Issue 1 , Pages 55–67; Published Online: 19 September 2003
The Two Fluid Model of Superfluid Helium, S. Yuan, (viewed 4 April 2005)
Rollin Film Rates in Liquid Helium, Henry A. Fairbank and C. T. Lane, Phys. Rev. 76, 1209–1211 (1949), from the online archive
Introduction to Liquid Helium, at the NASA Goddard Space Flight Center (viewed 4 April 2005)
Tests of vacuum VS helium in a solar telescope, Engvold, O.; Dunn, R. B.; Smartt, R. N.; Livingston, W. C.. Applied Optics, vol. 22, 1 January 1983, p. 10–12
Bureau of Mines (1967). Minerals yearbook mineral fuels Year 1965, Volume II (1967). U. S. Government Printing Office.
Helium: Fundamental models, Don L. Anderson, G. R. Foulger & Anders Meibom (viewed 5 April 2005)
High Pressure Nervous Syndrome, Diving Medicine Online (viewed 5 April 2005)

Table

Nuclides and Isotopes Fourteenth Edition: Chart of the Nuclides, General Electric Company, 1989
WebElements.com and EnvironmentalChemistry.com per the guidelines at Wikipedia's WikiProject Elements (viewed 10 October 2002)

Notes

^ ^a ^b The Encyclopedia of the Chemical Elements, edited by Cifford A. Hampel, "Helium" entry by L. W. Brandt (New York; Reinhold Book Corporation; 1968; page 261) Library of Congress Catalog Card Number: 68-29938
^ ^a ^b ^c Los Alamos National Laboratory (LANL.gov): Periodic Table, "Helium" (viewed 10 October 2002 and 25 March 2005)
^ C. Malinowska-Adamska, P. Soma, J. Tomaszewski. "Dynamic and thermodynamic properties of solid helium in the reduced all-neighbours approximation of the self-consistent phonon theory". physica status solidi (b) 240 (1): 55-67. doi:10.1002/pssb.200301871.
^ Solid Helium, Dept. of Physics, at the University of Alberta
^ Structure of Solid Helium by Neutron Diffraction, D. G. Henshaw, Physical Review Letters 109, Pg. 328 – 330 (Issue 2 – January 1958)
^ ^a ^b ^c The Encyclopedia of the Chemical Elements, page 262
^ Yuan, Sidney. The Two Fluid Model of Superfluid Helium (He II, Superfluidity). Yutiopian.com. Retrieved on 5 January 2007.
^ ^a ^b The Encyclopedia of the Chemical Elements, page 263
^ (October 1949) "Rollin Film Rates in Liquid Helium". Physical Review 76 (8): 1209–1211. doi:10.1103/PhysRev.76.1209.
^ Ellis, Fred M. Third sounds. Wesleyan Quantum Fluids Laboratory. Retrieved on 2007-11-08.
^ Warner, Brent. Introduction to Liquid Helium. NASA. Archived from the original on 2005-09-01. Retrieved on 2007-01-05.
^ Physics in speech, phys.unsw.edu.au. Retrieved on 5 January 2007.
^ The Encyclopedia of the Chemical Elements, page 256
^ Oxford English Dictionary (1989), s.v. "helium". Retrieved on December 16, 2006, from Oxford English Dictionary Online. Also, from quotation there: Thomson, W. (1872). Rep. Brit. Assoc. xcix: "Frankland and Lockyer find the yellow prominences to give a very decided bright line not far from D, but hitherto not identified with any terrestrial flame. It seems to indicate a new substance, which they propose to call Helium."
^ ^a ^b ^c The Encyclopedia of the Chemical Elements, page 257
^ William Ramsay (1895). "On a Gas Showing the Spectrum of Helium, the Reputed Cause of D3 , One of the Lines in the Coronal Spectrum. Preliminary Note". Proceedings of the Royal Society of London 58: 65-67.
^ William Ramsay (1895). "Helium, a Gaseous Constituent of Certain Minerals. Part I". Proceedings of the Royal Society of London 58: 80-89.
^ William Ramsay (1895). "Helium, a Gaseous Constituent of Certain Minerals. Part II--". Proceedings of the Royal Society of London 59: 325-330.
^ ^a ^b Emsley, Nature's Building Blocks, 177
^ Pat Munday (1999). Biographical entry for W.F. Hillebrand (1853–1925), geochemist and US Bureau of Standards administrator in American National Biography, ed. John A. Garraty and Mark C. Carnes, 24 vols. (Oxford University Press: 1999): v. 10, pp. 808–9; v. 11, pp. 227-8.
^ ^a ^b Emsley, Nature's Building Blocks, 179
^ American Chemical Society (2004). The Discovery of Helium in Natural Gas. Retrieved on 2006-05-17.
^ (1961) "Aeronautics and Astronautics Chronology, 1920-1924", in Eugene M. Emme, comp.: Aeronautics and Astronautics: An American Chronology of Science and Technology in the Exploration of Space, 1915-1960. Washington, DC: NASA, 11–19.
^ Guide to the Elements: Revised Edition, by Albert Stwertka (New York; Oxford University Press; 1998; page 24) ISBN 0-19-512708-0
^ Helium Privatization Act of 1996. Retrieved on 2007-01-05.
^ Executive Summary, nap.edu. Retrieved on 5 January 2007.
^ The Atmosphere: Introduction. JetStream - Online School for Weather. National Weather Service.
^ Lie-Svendsen, Ø.; Rees, M. H. (1996). "Helium escape from the terrestrial atmosphere: The ion outflow mechanism". Journal of Geophysical Research 101 (A2): 2435–2444. doi:10.1029/95JA02208.
^ Strobel, Nick (2007). Nick Strobel's Astronomy Notes. Retrieved on 2007-09-25.
^ WebElements Periodic Table: Professional Edition: Helium: key information
^ The Encyclopedia of the Chemical Elements, page 258
^ Emsley, John. Nature's Building Blocks: An A-Z Guide to the Elements. Oxford: Oxford University Press, 2001. Page 178. ISBN 0-19-850340-7
^ (April 2002) "Isotopic Composition and Abundance of Interstellar Neutral Helium Based on Direct Measurements". Astrophysics 45 (2): 131–142. Retrieved on 2007-01-05.
^ The Encyclopedia of the Chemical Elements, page 264
^ ^a ^b http://www.mantleplumes.org/HeliumFundamentals.html
^ http://environmentalchemistry.com/yogi/periodic/Li-pg2.html
^ The Encyclopedia of the Chemical Elements, page 260
^ The Encyclopedia of the Chemical Elements, page 264
^ Stay Out of That Balloon! The dangers of helium inhalation, Slate.com. Retrieved on 18 September 2007.
^ HPNS, scuba-doc.com. Retrieved on 5 January 2007.