2 hydrogen ← helium → lithium - ↑ He ↓ Ne Periodic Table - Extended Periodic Table
General
Name, Symbol, Number	helium, He, 2
Chemical series	noble gases
Group, Period, Block	18, 1, s
Appearance	colorless
Atomic mass	4.002602(2) g/mol
Electron configuration	1s2
Electrons per shell	2
Physical properties
Phase	gas
Density	(0 °C, 101.325 kPa) 0.1786 g/L
Melting point	(at 2.5 MPa) 0.95 K (-272.2 °C, -458.0 °F)
Boiling point	4.22 K (-268.93 °C, -452.07 °F)
Critical point	5.19 K, 0.227 MPa
Heat of fusion	0.0138 kJ·mol−1
Heat of vaporization	0.0829 kJ·mol−1
Heat capacity	(25 °C) 20.786 J·mol−1·K−1
Vapor pressure P/Pa 1 10 100 1 k 10 k 100 k at T/K         3 4
Atomic properties
Crystal structure	hexagonal or bcc
Ionization energies	1st: 2372.3 kJ/mol
	2nd: 5250.5 kJ/mol
Atomic radius (calc.)	31 pm
Covalent radius	32 pm
Van der Waals radius	140 pm
Miscellaneous
Thermal conductivity	(300 K) 151.3 mW·m−1·K−1
CAS registry number	7440-59-7
Selected isotopes
Main article: Isotopes of helium iso NA half-life DM DE (MeV) DP 3He 0.000137%* He is stable with 1 neutron 4He 99.999863%* He is stable with 2 neutrons *Atmospheric value, abundance may differ elsewhere.
References

For other uses of this term, see Helium (disambiguation).

Helium is a colorless, odorless, tasteless chemical element, the least reactive of the nearly inert noble gases of the periodic table. Its boiling and melting points are the lowest among the elements; except in extreme conditions, it exists only as a gas. At temperatures near absolute zero, it is a superfluid, a nearly frictionless phase of matter with unusual properties. Image File history File links LinkFA-star. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... General Name, Symbol, Number lithium, Li, 3 Chemical series alkali metals Group, Period, Block 1, 2, s Appearance silvery white/grey Atomic mass 6. ... General Name, Symbol, Number neon, Ne, 10 Chemical series noble gases Group, Period, Block 18, 2, p Appearance colorless Atomic mass 20. ... Download high resolution version (900x270, 18 KB) Wikipedia does not have an article with this exact name. ... This is a standard display of the periodic table of elements. ... This extended periodic table was suggested by Glenn T. Seaborg in 1969. ... This is a list of chemical elements, sorted by name and color coded according to type of element. ... Categories: Chemical elements ... sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex... For the musical band, see Noble Gas (band) The noble gases are the chemical elements in group 18 (old-style Group 0) of the periodic table. ... A periodic table group is a vertical column in the periodic table of the chemical elements. ... In the periodic table of the elements, a period is a row of the table. ... A block of the periodic table of elements is a set of adjacent groups. ... The noble gases are a chemical series. ... A period 1 element is one of the chemical elements in the first row (or period) of the periodic table of the elements. ... The s-block of the periodic table of elements consists of the first two groups: the alkali metals and alkaline earth metals, plus hydrogen. ... Color is an important part of the visual arts. ... ImageMetadata File history File links He,2. ... The atomic mass of a chemical element is the mass of an atom at rest, most often expressed in unified atomic mass units. ... To help compare different orders of magnitude we list here masses between 0. ... Hydrogen = 1 List of Elements in Atomic Number Order. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... The electron is a fundamental subatomic particle that carries an electric charge. ... Example of a sodium electron shell model An electron shell, also known as a main energy level, is a group of atomic orbitals with the same value of the principal quantum number n. ... In the physical sciences, a phase is a set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties (i. ... A gas is one of the four major phases of matter (after solid and liquid, and followed by plasma, that subsequently appear as a solid material is subjected to increasingly higher temperatures. ... Density (symbol: ρ - Greek: rho) is a measure of mass per volume. ... The melting point of a crystalline solid is the temperature at which it changes state from solid to liquid. ... The Kelvin scale is a thermodynamic (absolute) temperature scale where absolute zero—the lowest possible temperature where nothing could be colder and no heat energy remains in a substance—is defined as zero kelvin (0 K). ... Celsius is, or relates to, the Celsius temperature scale. ... Fahrenheit is a temperature scale named after the German physicist Daniel Gabriel Fahrenheit (1686–1736), who proposed it in 1724. ... The boiling point of a substance is the temperature at which it can change its state from a liquid to a gas throughout the bulk of the liquid at a given pressure. ... The Kelvin scale is a thermodynamic (absolute) temperature scale where absolute zero—the lowest possible temperature where nothing could be colder and no heat energy remains in a substance—is defined as zero kelvin (0 K). ... Celsius is, or relates to, the Celsius temperature scale. ... Fahrenheit is a temperature scale named after the German physicist Daniel Gabriel Fahrenheit (1686–1736), who proposed it in 1724. ... In physical chemistry, thermodynamics, chemistry and condensed matter physics, a critical point, also called a critical state, specifies the conditions (temperature, pressure) at which the liquid state of the matter ceases to exist. ... The Kelvin scale is a thermodynamic (absolute) temperature scale where absolute zero—the lowest possible temperature where nothing could be colder and no heat energy remains in a substance—is defined as zero kelvin (0 K). ... Standard enthalpy change of fusion of period three. ... Kilojoule per mole are an SI derived unit of energy per amount of material, where energy is measured in units of 1000 joules, and the amount of material is measured in mole units. ... The standard enthalpy change of vaporization, ΔvHo, also (less correctly) known as the heat of vaporization is the energy required to transform a given quantity of a substance into a gas. ... Kilojoule per mole are an SI derived unit of energy per amount of material, where energy is measured in units of 1000 joules, and the amount of material is measured in mole units. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... In chemistry and physics, Vapor pressure is the pressure of a vapor in equilibrium with its non-vapor phases. ... Enargite crystals In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. ... The ionization energy (IE) of an atom or of a molecule is the energy required to strip it of an electron. ... Kilojoule per mole are an SI derived unit of energy per amount of material, where energy is measured in units of 1000 joules, and the amount of material is measured in mole units. ... To help compare different orders of magnitude this page lists lengths between 10 pm and 100 pm (10-11 m and 10-12 m). ... Covalent radius in chemistry corresponds to half of the distance between two identical atomic nuclei, bound by a covalent bond. ... To help compare different orders of magnitude this page lists lengths between 10 pm and 100 pm (10-11 m and 10-12 m). ... The van der Waals radius of an atom is the radius of an imaginary hard sphere which can be used to model the atom for many purposes. ... You have big harry skanky balls ... In physics, thermal conductivity, k, is the intensive property of a material that indicates its ability to conduct heat. ... CAS registry numbers are unique numerical identifiers for chemical compounds, polymers, biological sequences, mixtures and alloys. ... Helium (He) Standard atomic mass: 4. ... Isotopes are any of the several different forms of an element each having different atomic mass. ... Natural abundance refers to the prevalence of different isotopes of an element as found in nature. ... Half-Life For a quantity subject to exponential decay, the half-life is the time required for the quantity to fall to half of its initial value. ... In physics, the decay mode describes a particular way a particle decays. ... The decay energy is the energy released by a nuclear decay. ... An electronvolt (symbol: eV) is the amount of energy gained by a single unbound electron when it falls through an electrostatic potential difference of one volt. ... In nuclear physics, a decay product, also known as a daughter product, is a nuclide resulting from the radioactive decay of a parent or precursor nuclide. ... This article needs to be cleaned up to conform to a higher standard of quality. ... This article or section does not cite its references or sources. ... This article needs to be cleaned up to conform to a higher standard of quality. ... This article or section does not cite its references or sources. ... Recommended values for many properties of the elements, together with various references, are collected on these data pages. ... Helium may refer to: Helium, the chemical element Helium-3, an isotope of helium Helium-4, an isotope of helium Helium (band), a rock band See also Helium dating, a method of age determination Helium flash, a stage of stellar evolution Helium fusion, a type of nuclear fusion This is... The periodic table of the chemical elements A chemical element, often called simply an element, is a substance that cannot be decomposed or transformed into other chemical substances by ordinary chemical processes. ... For the musical band, see Noble Gas (band) The noble gases are the chemical elements in group 18 (old-style Group 0) of the periodic table. ... The periodic table of the chemical elements, also called the Mendeleev periodic table, is a tabular display of the known chemical elements. ... The boiling point of a substance is the temperature at which it can change its state from a liquid to a gas throughout the bulk of the liquid at a given pressure. ... The melting point of a crystalline solid is the temperature at which it changes state from solid to liquid. ... A gas is one of the four major phases of matter (after solid and liquid, and followed by plasma, that subsequently appear as a solid material is subjected to increasingly higher temperatures. ... Absolute zero is the lowest possible temperature where nothing could be colder and no heat energy remains in a substance. ... Helium II will creep along surfaces in order to find its own level - after a short while, the levels in the two containers will equalize. ...

After hydrogen, helium is the second lightest element and the second most abundant element in the universe, created during big bang nucleosynthesis and to a lesser extent from nuclear fusion of hydrogen in stars. On Earth, helium is relatively rare and is primarily a product of the radioactive decay of much heavier elements, which emit helium nuclei called alpha particles; it is found in significant amounts only in natural gas, from which it is extracted at low temperatures by fractional distillation. General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... The deepest visible-light image of the cosmos, the Hubble Ultra Deep Field. ... In cosmology, Big Bang nucleosynthesis (or primordial nucleosynthesis) refers to the production of nuclei other than H-1, the normal, light hydrogen, during the early phases of the universe, shortly after the Big Bang. ... The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ... The Pleiades, an open cluster of stars in the constellation of Taurus. ... Radioactive decay is the set of various processes by which unstable atomic nuclei emit subatomic particles (radiation). ... An alpha particle is deflected by a magnetic field Alpha particles (named after the first letter in the Greek alphabet, α) are a highly ionizing form of particle radiation which have low penetration. ... Natural gas is a gaseous fossil fuel consisting primarily of methane. ... Fractional distillation is the separation of a mixture into its component parts, or fractions, such as in separating chemical compounds by their boiling point by heating them to a temperature at which several fractions of the compound will evaporate. ...

First detected in 1868 by French astronomer Pierre Janssen as an unknown yellow spectral line signature in the light of a solar eclipse, helium was separately identified as a new element later that year by English astronomer Norman Lockyer. Its presence in natural gas in large, useable amounts was identified in 1905. Helium is used in cryogenics, as a deep-sea breathing gas, for inflating balloons and airships, and as a protective gas for many industrial purposes, such as arc welding. Inhaling a small amount of the gas temporarily changes the frequency of a person's voice; however, caution must be exercised as helium is an asphyxiant. Pierre Jules César Janssen (February 22, 1824 – December 23, 1907) was a French astronomer who in 1868 discovered how to observe solar prominences without an eclipse. ... Extremely high resolution spectrum of the Sun showing thousands of elemental absorption lines (fraunhofer lines) Spectroscopy is the study of matter and its properties by investigating light, sound, or particles that are emitted, absorbed or scattered by the matter under investigation. ... Photo taken during the 1999 eclipse. ... Sir Joseph Norman Lockyer or Norman Lockyer (May 17, 1836 – August 16, 1920) was an English scientist and astronomer. ... Cryogenics is a branch of physics (or engineering) that studies the production of very low temperatures (below –150 °C, –238 °F or 123 K) and the behavior of materials at those temperatures. ... Air is the most common and only natural breathing gas. ... Balloons, like greeting cards or flowers, are given for special occasions. ... USS Akron (ZRS-4) in flight, November 2, 1931 An airship or dirigible is a buoyant aircraft that can be steered and propelled through the air. ... Manual Metal Arc welding, also known as stick or MMA welding is one of the most common forms of welding. ... Asphyxia is a condition of severely deficient supply of oxygen to the body. ...

Notable characteristics

Gas and plasma phases

Helium is a colorless, odorless, and non-toxic gas. It is the least reactive member of the noble gases of the periodic table and thus also the least reactive of all elements; it is inert and monatomic in virtually all conditions. It has a thermal conductivity that is greater than any gas except hydrogen and its specific heat is unusually high. Helium is also less water soluble than any other gas known and its diffusion rate through solids is three times that of air and around 65% that of hydrogen.^[1] Helium's index of refraction is closer to unity than any other gas. Helium has a negative Joule-Thomson coefficient at normal ambient temperatures, meaning it heats up when allowed to freely expand. Only below its Joule-Thomson inversion temperature (of about 40 K at 1 atmosphere) does it cool upon free expansion. Once precooled below this temperature, helium can be liquefied through expansion cooling. For the musical band, see Noble Gas (band) The noble gases are the chemical elements in group 18 (old-style Group 0) of the periodic table. ... In English, to be inert is to be in a state of doing little or nothing. ... In physics and chemistry, monatomic is a combination of the words mono and atomic, and means single atom. ... In physics, thermal conductivity, k, is the intensive property of a material that indicates its ability to conduct heat. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... The specific heat capacity (symbol c or s, also called specific heat) of a substance is defined as heat capacity per unit mass. ... It has been suggested that Solid solubility be merged into this article or section. ... diffusion (disambiguation). ... In jewelry, a solid gold piece is the alternative to gold-filled or gold-plated jewelry. ... The refractive index of a material is the factor by which electromagnetic radiation is slowed down (relative to vacuum) when it travels inside the material. ... The Joule-Thomson effect is a physical process in which the temperature of a gas is decreased by letting the gas expand adiabatically. ... The Joule-Thomson effect is a physical process in which the temperature of a gas is decreased by letting the gas expand adiabatically. ... The Kelvin scale is a thermodynamic (absolute) temperature scale where absolute zero—the lowest possible temperature where nothing could be colder and no heat energy remains in a substance—is defined as zero kelvin (0 K). ...

Helium discharge tube shaped like the element's atomic symbol

Helium is chemically unreactive under all normal conditions due to its valence of zero. It is an electrical insulator unless ionized. As with the other noble gases, helium has metastable energy levels that allow it to remain ionized in an electrical discharge with a voltage below its ionization potential. Helium can form unstable compounds with tungsten, iodine, fluorine, sulfur and phosphorus when it is subjected to an electric glow discharge, through electron bombardment or is otherwise a plasma. HeNe, HgHe₁₀, WHe₂ and the molecular ions He₂⁺, He₂⁺⁺, HeH⁺, and HeD⁺ have been created this way. This technique has also allowed the production of the neutral molecule He₂, which has a large number of band systems, and HgHe, which is apparently only held together by polarization forces.^[1] Theoretically, other compounds, like helium fluorohydride (HHeF), may also be possible. ImageMetadata File history File links Download high resolution version (1024x768, 118 KB) Summary Image of a helium filled discharge tube shaped like the elements atomic symbol. ... ImageMetadata File history File links Download high resolution version (1024x768, 118 KB) Summary Image of a helium filled discharge tube shaped like the elements atomic symbol. ... Valence is a scientific term in chemistry to describe electrons in the outermost orbital. ... An ion is an atom or group of atoms that normally are electrically neutral and achieve their status as an ion by loss or addition of one or more electrons. ... A quantum mechanical system can only be in certain states, so that only certain energy levels are possible. ... Lightning strikes during a night-time thunderstorm. ... International safety symbol Caution, risk of electric shock (ISO 3864), colloquially known as high voltage symbol. ... The ionization potential, or ionization energy, of an atom or molecule is the energy required to strip it of an electron. ... A chemical compound is a chemical substance formed from two or more elements, with a fixed ratio determining the composition. ... General Name, Symbol, Number tungsten, W, 74 Chemical series transition metals Group, Period, Block 6, 6, d Appearance grayish white, lustrous Atomic mass 183. ... General Name, Symbol, Number iodine, I, 53 Chemical series halogens Group, Period, Block 17, 5, p Appearance violet-dark gray, lustrous Atomic mass 126. ... General Name, Symbol, Number fluorine, F, 9 Chemical series halogens Group, Period, Block 17, 2, p Appearance Yellowish brown gas Atomic mass 18. ... General Name, Symbol, Number sulfur, S, 16 Chemical series nonmetals Group, Period, Block 16, 3, p Appearance lemon yellow Atomic mass 32. ... General Name, Symbol, Number phosphorus, P, 15 Chemical series nonmetals Group, Period, Block 15, 3, p Appearance waxy white/ red/ black/ colorless Atomic mass 30. ... now. ... A Plasma lamp In physics and chemistry, a plasma is an ionized gas, and is usually considered to be a distinct phase of matter. ...

Throughout the universe, helium is found mostly in a plasma state whose properties are quite different to molecular helium. As a plasma, helium's electrons and protons are not bound together, resulting in very high electrical conductivity, even when the gas is only partially ionized. The charged particles are highly influenced by magnetic and electric fields. For example, in the solar wind together with ionized hydrogen, they interact with the Earth's magnetosphere giving rise to Birkeland currents and the aurora. A Plasma lamp, illustrating some of the more complex phenomena of a plasma, including filamentation A solar coronal mass ejection blasts plasma throughout the solar system. ... The plasma in the solar wind meeting the heliopause For the British comic, see Solar Wind (comic). ... A magnetosphere is the region around an astronomical object in which phenomena are dominated or organized by its magnetic field. ... The aurora on Jupiter, powered by Jovian Birkeland currents [Ref. ... Aurora borealis Aurora borealis The aurora is a glow observed in the night sky, usually in the polar zone. ...

Solid and liquid phases

Helium solidifies only under great pressure. The resulting colorless, almost invisible solid is highly compressible; applying pressure in the laboratory can decrease its volume by more than 30%.^[2] With a bulk modulus on the order of 5×10⁷ Pa^[3] it is 50 times more compressible than water. Unlike any other element, helium will fail to solidify and remain a liquid down to absolute zero at normal pressures. This is a direct effect of quantum mechanics: specifically, the zero point energy of the system is too high to allow freezing. Solid helium requires a temperature of 1–1.5 K (about −272 °C or −457 °F) and about 26 standard atmospheres (2.6 MPa) of pressure.^[4] It is often hard to distinguish solid from liquid helium since the refractive index of the two phases are nearly the same. The solid has a sharp melting point and has a crystalline structure. In jewelry, a solid gold piece is the alternative to gold-filled or gold-plated jewelry. ... Fluid Dynamics Compressibility (physics) is a measure of the relative volume change of fluid or solid as a response to a pressure (or mean stress) change: . For a gas the magnitude of the compressibility depends strongly on whether the process is adiabatic or isothermal, while this difference is small in... The bulk modulus K of a fluid or solid is the inverse of the compressibility: where p is pressure and V is volume. ... The pascal (symbol: Pa) is the SI derived unit of pressure or stress (also: Youngs modulus and tensile strength). ... Absolute zero is the lowest possible temperature where nothing could be colder and no heat energy remains in a substance. ... In a quantum mechanical system such as the particle in a box or the quantum harmonic oscillator, the lowest possible energy is called the zero-point energy. ... Helium exists in liquid form only at very low temperatures. ... The refractive index (or index of refraction) of a material is the factor by which the phase velocity of electromagnetic radiation is slowed in that material, relative to its velocity in a vacuum. ... The melting point of a crystalline solid is the temperature at which it changes state from solid to liquid. ... Quartz crystal In chemistry and mineralogy, a crystal is a solid in which the constituent atoms, molecules, or ions are packed in a regularly ordered, repeating pattern extending in all three spatial dimensions. ...

Helium I state

Below its boiling point of 4.22 kelvin and above the lambda point of 2.1768 kelvin, the isotope helium-4 exists in a normal colorless liquid state, called helium I. Like other cryogenic liquids, helium I boils when heat is added to it. It also contracts when its temperature is lowered until it reaches the 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. The boiling point of a substance is the temperature at which it can change its state from a liquid to a gas throughout the bulk of the liquid at a given pressure. ... The Kelvin scale is a thermodynamic (absolute) temperature scale where absolute zero—the lowest possible temperature where nothing could be colder and no heat energy remains in a substance—is defined as zero kelvin (0 K). ... Lambda point is the temperature (approximately 2. ... Isotopes are any of the several different forms of an element each having different atomic mass. ... A liquid will usually assume the shape of its container. ... Lambda point is the temperature (approximately 2. ...

Helium I has a gas-like index of refraction of 1.026 which makes its surface so hard to see that floats of Styrofoam are often used to show where the surface is.^[5] This colorless liquid has a very low viscosity and a density 1/8th that of water, which is only 1/4th the value expected from classical physics.^[5] Quantum mechanics is needed to explain this property and thus both types of liquid helium are called quantum fluids, meaning they display atomic properties on a macroscopic scale. This is probably due to its boiling point being so close to absolute zero, which prevents random molecular motion (heat) from masking the atomic properties.^[5] The refractive index of a material is the factor by which electromagnetic radiation is slowed down (relative to vacuum) when it travels inside the material. ... Styrofoam is a trademark name for extruded polystyrene thermal insulation material, manufactured by Dow Chemical Company. ... The pitch drop experiment at the University of Queensland. ... Density (symbol: ρ - Greek: rho) is a measure of mass per volume. ... Water is an odourless substance that is essential to all known forms of life and is known as the universal solvent. ... Classical physics is physics based on principles developed before the rise of quantum theory, usually including the special theory of relativity and general theory of relativity. ... Fig. ... In physics, heat, symbolized by Q, is defined as energy in transit. ...

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 thermal conductivity; heat input instead causes evaporation of the liquid directly to gas. The isotope helium-3 also has a superfluid phase, but only at much lower temperatures; as a result, less is known about such properties in the isotope helium-3. In physics, thermal conductivity, k, is the intensive property of a material that indicates its ability to conduct heat. ... This article or section is in need of attention from an expert on the subject. ...

Helium II will "creep" along surfaces in order to find its own level - after a short while, the levels in the two containers will equalize. The Rollin film also covers the interior of the larger container; if it were not sealed, the helium II would creep out and escape.

Helium II is a superfluid, a quantum-mechanical state of matter with strange properties. For example, when it flows through even capillaries of 10^-7 to 10^-8 m width it has no measurable 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.^[6] Wikipedia does not have an article with this exact name. ... Wikipedia does not have an article with this exact name. ... A Rollin film is a 30 nm thick liquid film of Helium in the Helium II state. ... Helium II will creep along surfaces in order to find its own level - after a short while, the levels in the two containers will equalize. ... The pitch drop experiment at the University of Queensland. ... In physics, the ground state of a quantum mechanical system is its lowest-energy state. ...

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 Rollin film and is named after the man who first characterized this trait, Bernard V. Rollin.^[7][8] As a result of this creeping behavior and helium II's ability to leak rapidly through tiny openings, it is very difficult to confine liquid helium. Unless the container is carefully constructed, the helium II will creep along the surfaces and through valves until it reaches somewhere warmer, where it will evaporate. Gravity is a force of attraction that acts between bodies that have mass. ... A metre (American spelling: meter; symbol: m) is a unit of length and the current base unit of length in the International System of Units (SI). ... A Rollin film is a 30 nm thick liquid film of Helium in the Helium II state. ...

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.^[9] Sintering is a method for making objects from powder, increasing the adhesion between particles as they are heated. ...

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 copper. This is because heat conduction occurs by an exceptional quantum-mechanical mechanism. Most materials that conduct heat well have a valence band of free electrons which serve to transfer the heat. Helium II has no such valence band but nevertheless conducts heat well. The flow of heat is governed by equations that are similar to the wave equation used to characterize sound propagation in air. So when heat is introduced, it will move at 20 meters per second at 1.8 K through helium II as waves in a phenomenon called second sound.^[7] General Name, Symbol, Number copper, Cu, 29 Chemical series transition metals Group, Period, Block 11, 4, d Appearance metallic pinkish red Atomic mass 63. ... In solids, the valence band is the highest range of electron energies where electrons are normally present at zero temperature. ... In thermal physics, heat transfer is the passage of thermal energy from a hot to a cold object. ... An equation is a mathematical statement, in symbols, that two things are the same. ... The wave equation is an important partial differential equation that describes a variety of waves, such as sound waves, light waves and water waves. ... It has been suggested that this article be split into articles entitled Sound, Sound pressure and Sound pressure level, accessible from a disambiguation page. ...

Applications

Because of its low density, helium is the gas of choice to fill airships such as the Goodyear blimp

Helium is used for many purposes that require some of its unique properties, such as its low boiling point, low density, low solubility, high thermal conductivity, or inertness. Pressurized helium is commercially available in large quantities. This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... USS Akron (ZRS-4) in flight, November 2, 1931 An airship or dirigible is a buoyant aircraft that can be steered and propelled through the air. ... The Spirit of Goodyear has a distinctive yellow stripe under the logo. ... The boiling point of a substance is the temperature at which it can change its state from a liquid to a gas throughout the bulk of the liquid at a given pressure. ... Density (symbol: ρ - Greek: rho) is a measure of mass per volume. ... It has been suggested that Solid solubility be merged into this article or section. ... In physics, thermal conductivity, k, is the intensive property of a material that indicates its ability to conduct heat. ... In English, to be inert is to be in a state of doing little or nothing. ...

• Because it is lighter than air, airships and balloons are inflated with helium for lift. In airships, helium is preferred over hydrogen because it is not flammable and has 92.64% of the lifting power of the alternative hydrogen.
• For its low solubility in water, the major part of human blood, air mixtures of helium with oxygen and nitrogen (Trimix), with oxygen only (Heliox), with common air (heliair), and with hydrogen and oxygen (hydreliox), are used in deep-sea breathing systems to reduce the high-pressure risk of nitrogen narcosis, decompression sickness, and oxygen toxicity.
• At extremely low temperatures, liquid helium is used to cool certain metals to produce superconductivity, such as in superconducting magnets used in magnetic resonance imaging. Helium at low temperatures is also used in cryogenics.
• For its inertness and high thermal conductivity, helium is used as a coolant in some nuclear reactors, such as pebble-bed reactors, and in arc welding air-sensitive metals.
• Because it is inert, helium is used as a protective gas in growing silicon and germanium crystals, in titanium and 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 hydrogen and oxygen to make 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 gain medium of the helium-neon laser is a mixture of helium and neon.
• Because it diffuses through solids at a rate three times that of air, helium is used to detect leaks in high-vacuum equipment and high-pressure containers.
• 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 rocks and minerals that contain uranium and thorium, radioactive elements that emit helium nuclei called alpha particles, can be discovered by measuring the level of helium with a process known as helium dating.
• Because helium alone is less dense than atmospheric air, it will change the timbre (not pitch ^[10]) 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 number of contaminants that may be present. These could include trace amount of other gases, in addition to aerosolized lubricating oil.
• 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.

The expression lighter than air refers to objects, usually aircraft, that are buoyant in air because they have an average density that is less than that of air (usually because they contain gases that have a density that is lower than that of air). ... USS Akron (ZRS-4) in flight, November 2, 1931 An airship or dirigible is a buoyant aircraft that can be steered and propelled through the air. ... Balloons, like greeting cards or flowers, are given for special occasions. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... Human blood smear: a - erythrocytes; b - neutrophil; c - eosinophil; d - lymphocyte. ... General Name, Symbol, Number oxygen, O, 8 Chemical series Nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Atomic mass 15. ... General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless Atomic mass 14. ... Trimix is a breathing gas, consisting of oxygen, helium and nitrogen, and is often used during the deep phase of dives carried out using Technical diving techniques. ... Heliox is a gas that is composed of a mixture of helium (He) and oxygen (O2). ... Heliair is a breathing gas consisting of mixture of oxygen, nitrogen and helium and is often used during the deep phase of dives carried out using technical diving techniques. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... Hydreliox is an exotic gas mixture used primarily for research and scientific deep diving, usually below 130 metres (429 feet). ... Nitrogen narcosis or inert gas narcosis is a reversible alteration in consciousness producing a state similar to alcohol intoxication in SCUBA divers at depth. ... Oxygen toxicity or oxygen toxicity syndrome is severe hyperoxia caused by breathing oxygen at elevated partial pressures. ... A magnet levitating above a high-temperature superconductor (with boiling liquid nitrogen underneath), demonstrating the Meissner effect. ... Superconducting magnets are electromagnets that are built using superconducting coils. ... This article or section does not cite its references or sources. ... Cryogenics is a branch of physics (or engineering) that studies the production of very low temperatures (below –150 °C, –238 °F or 123 K) and the behavior of materials at those temperatures. ... In physics, thermal conductivity, k, is the intensive property of a material that indicates its ability to conduct heat. ... Nuclear power station at Leibstadt, Switzerland. ... The Pebble Bed Reactor is an advanced nuclear reactor design. ... Manual Metal Arc welding, also known as stick or MMA welding is one of the most common forms of welding. ... General Name, Symbol, Number silicon, Si, 14 Chemical series metalloids Group, Period, Block 14, 3, p Appearance as coarse powder, dark gray with bluish tinge Atomic mass 28. ... General Name, Symbol, Number germanium, Ge, 32 Chemical series metalloids Group, Period, Block 14, 4, p Appearance grayish white Atomic mass 72. ... General Name, Symbol, Number titanium, Ti, 22 Chemical series transition metals Group, Period, Block 4, 4, d Appearance silvery metallic Atomic mass 47. ... General Name, Symbol, Number zirconium, Zr, 40 Chemical series transition metals Group, Period, Block 4, 5, d Appearance silvery white Atomic mass 91. ... Gas-liquid chromatography (GLC), or simply gas chromatography (GC) is a type of chromatography in which the mobile phase is a carrier gas, usually an inert gas such as helium or nitrogen, and the stationary phase is a microscopic layer of liquid on an inert solid support. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... A rocket is a vehicle, missile or aircraft which obtains thrust by the reaction to the ejection of fast moving exhaust from within a rocket engine. ... In a barrel or wine bottle, for example, ullage is the space within the container but above the liquid. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... General Name, Symbol, Number oxygen, O, 8 Chemical series Nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Atomic mass 15. ... Rocket fuel is a propellant that reacts with an oxidizing agent to produce thrust in a rocket. ... Space exploration is the physical exploration of outer-Earth objects and generally anything that involves the technologies, science, and politics regarding space endeavors. ... This article is about the rocket. ... Description Role: Earth and Lunar Orbit Crew: 3; CDR, CM pilot, LM pilot Dimensions Height: 36. ... A laser system generally consists of three important parts: An energy source (usually referred to as the pump or pump source); A gain medium or laser medium; A mirror, or system of mirrors, forming an optical resonator. ... A helium-neon laser, usually called a HeNe laser, is a type of small gas laser. ... General Name, Symbol, Number neon, Ne, 10 Chemical series noble gases Group, Period, Block 18, 2, p Appearance colorless Atomic mass 20. ... diffusion (disambiguation). ... The refractive index of a material is the factor by which electromagnetic radiation is slowed down (relative to vacuum) when it travels inside the material. ... Look up lens in Wiktionary, the free dictionary. ... 50 cm refracting telescope at Nice Observatory. ... The rocky side of a mountain creek near Orosí, Costa Rica. ... Minerals are natural compounds formed through geological processes. ... General Name, Symbol, Number uranium, U, 92 Chemical series actinides Group, Period, Block n/a, 7, f Appearance silvery gray metallic; corrodes to a spalling black oxide coat in air Atomic mass 238. ... General Name, Symbol, Number thorium, Th, 90 Chemical series Actinides Group, Period, Block n/a, 7, f Appearance silvery white Atomic mass 232. ... Radioactive decay is the set of various processes by which unstable atomic nuclei (nuclides) emit subatomic particles. ... An alpha particle is deflected by a magnetic field Alpha particles (named after the first letter in the Greek alphabet, α) are a highly ionizing form of particle radiation which have low penetration. ... Helium Dating (or He dating) is the method of age determination that depends on the production of helium during the decay of the radioactive isotopes uranium-235(U-235), uranium-238(U-238), and thorium-232(Th-232). ... In music, timbre, also timber (from Fr. ... Pitch may refer to: Look up Pitch in Wiktionary, the free dictionary. ... Sonic or thermoacoustic refrigeration is a technology that uses high-amplitude sound waves in a pressurised gas to pump heat from one place to another. ...

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 spectrum of the chromosphere of the Sun, by French astronomer Pierre Janssen during a total solar eclipse in Guntur, India. This line was initially assumed to be sodium. On October 20 of the same year, English astronomer Norman Lockyer observed a yellow line in the solar spectrum, which he named the D₃ line, for it was near the known D₁ and D₂ lines of sodium,^[11] and concluded that it was caused by an element in the Sun unknown on Earth. He and English chemist Edward Frankland named the element with the Greek word for the Sun, ἥλιος (helios)^[12] August 18 is the 230th day of the year (231st in leap years) in the Gregorian calendar. ... 1868 (MDCCCLXVIII) was a leap year starting on Wednesday (see link for calendar) of the Gregorian calendar or a leap year starting on Friday of the 12-day-slower Julian calendar. ... The wavelength is the distance between repeating units of a wave pattern. ... In most modern usages of the word spectrum, there is a unifying theme of between extremes at either end. ... The chromosphere (literally, color sphere) is a thin layer of the Suns atmosphere just above the photosphere, roughly 10,000 kilometers deep. ... The Sun is the star of our solar system. ... Pierre Jules César Janssen (February 22, 1824 – December 23, 1907) was a French astronomer who in 1868 discovered how to observe solar prominences without an eclipse. ... Photo taken during the 1999 eclipse. ... Guntur   (గుంటూరు in Telugu) is a city and a municipal corporation in the Indian state of Andhra Pradesh. ... General Name, Symbol, Number sodium, Na, 11 Chemical series alkali metals Group, Period, Block 1, 3, s Appearance silvery white Atomic mass 22. ... Sir Joseph Norman Lockyer or Norman Lockyer (May 17, 1836 – August 16, 1920) was an English scientist and astronomer. ... Solar Fraunhofer lines In physics and optics, the Fraunhofer lines are a set of spectral lines named for the German physicist Joseph von Fraunhofer (1787--1826). ... Sir Edward Frankland (January 18, 1825 – August 9, 1899) was an English chemist. ...

On March 26, 1895, British chemist William Ramsay isolated helium on Earth by treating the mineral cleveite with mineral acids. Ramsay was looking for argon but, after separating nitrogen and oxygen from the gas liberated by sulfuric acid, noticed a bright-yellow line that matched the D₃ line observed in the spectrum of the Sun.^[13] These samples were identified as helium by Lockyer and British physicist William Crookes. It was independently isolated from cleveite the same year by chemists Per Teodor Cleve and Abraham Langlet in Uppsala, Sweden, who collected enough of the gas to accurately determine its atomic weight.^[14] March 26 is the 85th day of the year in the Gregorian Calendar (86th in leap years). ... 1895 (MDCCCXCV) was a common year starting on Tuesday (see link for calendar) of the Gregorian calendar (or a common year starting on Thursday of the 12-day-slower Julian calendar). ... Sir William Ramsay (October 2, 1852 – July 23, 1916) was a Scottish chemist who discovered the noble gases and received the Nobel Prize in Chemistry in 1904 (along with Lord Rayleigh who received the Nobel Prize in Physics that same year for the discovery of argon). ... Cleveite is a radioactive mineral containing uranium and found in Norway. ... An acid (often represented by the generic formula HA) is traditionally considered any chemical compound that, when dissolved in water, gives a solution with a pH of less than 7. ... General Name, Symbol, Number argon, Ar, 18 Chemical series noble gases Group, Period, Block 18, 3, p Appearance colorless Atomic mass 39. ... General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless Atomic mass 14. ... General Name, Symbol, Number oxygen, O, 8 Chemical series Nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Atomic mass 15. ... Sulfuric acid (British English: sulphuric acid), H2SO4, is a strong mineral acid. ... Sir William Crookes, OM, FRS (17 June 1832 – 4 April 1919) was an English chemist and physicist. ... Per Teodor Cleve (Stockholm February 10, 1840 – Uppsala June 18, 1905) was a Swedish chemist and geologist. ... Nils Abraham Langlet (July 9, 1868 - March 30, 1936; known by his second given name) was a Swedish chemist. ... This article is about the modern city of Uppsala. ... The atomic mass of a chemical element is the mass of an atom at rest, most often expressed in unified atomic mass units. ...

In 1907, Ernest Rutherford and Thomas Royds demonstrated that an alpha particle is a helium nucleus. In 1908, helium was first liquefied by Dutch physicist Heike Kamerlingh Onnes by cooling the gas to less than one kelvin. He tried to solidify it by further reducing the temperature but failed because helium does not have a 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. Ernest Rutherford, 1st Baron Rutherford of Nelson OM PC FRS (30 August 1871 – 19 October 1937), was a nuclear physicist from New Zealand. ... An alpha particle is deflected by a magnetic field Alpha particles (named after the first letter in the Greek alphabet, α) are a highly ionizing form of particle radiation which have low penetration. ... A semi-accurate depiction of the helium atom. ... Heike Kamerlingh Onnes (September 21, 1853 – February 21, 1926) was a Dutch physicist. ... The Kelvin scale is a thermodynamic (absolute) temperature scale where absolute zero—the lowest possible temperature where nothing could be colder and no heat energy remains in a substance—is defined as zero kelvin (0 K). ... In physics, the triple point of a substance is the temperature and pressure at which three phases (gas, liquid, and solid) of that substance may coexist in thermodynamic equilibrium. ... Willem Hendrik Keesom (1876-1956) was a Dutch scientist who, in 1926, invented a method to solidify helium. ... When expressed as a measurement, an atmosphere (symbol: atm) or standard atmosphere is a unit of pressure roughly equal to the average atmospheric pressure at sea level on Earth. ...

In 1938, Russian physicist Pyotr Leonidovich Kapitsa discovered that helium-4 has almost no viscosity at temperatures near absolute zero, a phenomenon now called superfluidity. In 1972, the same phenomenon was observed in helium-3 by American physicists Douglas D. Osheroff, David M. Lee, and Robert C. Richardson. Semenov (on the right) and Kapitsa (on the left), portrait by Boris Kustodiev, 1921 Pyotr Leonidovich Kapitsa (Russian Пётр Леонидович Капица) (July 9, 1894 – April 8, 1984) was a Soviet/Russian physicist who discovered superfluidity with some contribution from John F. Allen and Don Misener in 1937. ... Helium-4 is a non-radioactive and light isotope of helium. ... The pitch drop experiment at the University of Queensland. ... Absolute zero is the lowest possible temperature where nothing could be colder and no heat energy remains in a substance. ... Superfluidity is a phase of matter characterised by the complete absence of viscosity. ... Douglas Dean Osheroff (born August 1, 1945) is a American physicist. ... This article needs to be wikified. ... There are at least two famous people with the name Robert C. Richardson. ...

Extraction and use

After an oil drilling operation in 1903 in Dexter, Kansas, USA 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.^[15] With further analysis, Cady and McFarland discovered that 1.84% of the gas sample was helium.^[16] Far from being a rare element, helium was present in vast quantities under the American Great Plains, available for extraction from natural gas. Dexter is a city located in Cowley County, Kansas. ... Erasmus Haworth, Ph. ... Hamilton Perkins Cady, (May 2, 1874 - May 26, 1943), was an American chemist who in 1907 in collaboration with David McFarland discovered that helium could be extracted 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.^[13] 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 December 1, 1921.^[17] Sir Richard Threlfall (August 14, 1861 - July 10, 1932) was an English chemist and engineer, he established the School of Physics at the University of Sydney and made important contributiosn to military scince during World War I. Threlfall was a son of Richard Threlfall of Hollowforth, near Preston, Lancashire. ... USN redirects here. ... Combatants Allied Powers: British Empire France Italy Russia United States Central Powers: Austria-Hungary Bulgaria Germany Ottoman Empire Commanders Ferdinand Foch Georges Clemenceau Joseph Joffre Victor Emmanuel III Luigi Cadorna Armando Diaz Nicholas II Aleksei Brusilov Herbert Henry Asquith Douglas Haig John Jellicoe Woodrow Wilson John Pershing Wilhelm II Paul... US Marine Corps barrage balloon, Parris Island, May 1942 A barrage balloon is a large balloon used as a defense against aircraft. ... USS Akron (ZRS-4) in flight, November 2, 1931 An airship or dirigible is a buoyant aircraft that can be steered and propelled through the air. ... Hampton Roads, Virginia 1858 Hampton Roads is the name of both a body of water and the land areas which surround it in southeastern Virginia in the United States. ... Bolling Air Force Base, in Southwest Washington, DC, is named for Col. ... Nickname: DC, The District Motto: Justitia Omnibus (Justice for All) Location of Washington, D.C., in relation to the states Maryland and Virginia. ... December 1 is the 335th (in leap years the 336th) day of the year in the Gregorian calendar. ... 1921 (MCMXXI) was a common year starting on Saturday (see link for calendar). ...

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. Welding is a fabrication process that joins materials, usually metals or thermoplastics, by causing coalescence. ... The Manhattan Project resulted in the development of the first nuclear weapons, and the first-ever nuclear detonation, at the Trinity test of July 16, 1945. ...

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. Helium use following World War II was depressed but the reserve was expanded in the 1950s to ensure a supply liquid helium as a coolant to create oxygen/hydrogen 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. ... The National Helium Reserve is an American strategic reserve of over a billion cubic feet of Helium gas, stored at the Cliffside Storage Facility about 12 miles northwest of Amarillo, Texas in a natural geologic gas storage formation. ... Nickname: The Yellow Rose of Texas, Helium Capital of the World, Rotor City USA Location within the state of Texas Coordinates: Country United States State Texas County Potter (and Randall) Mayor Debra McCartt Area    - City 233. ... USS Akron (ZRS-4) in flight, November 2, 1931 An airship or dirigible is a buoyant aircraft that can be steered and propelled through the air. ... A war is a conflict between two or more groups that involve large numbers of individuals. ... Combatants Major Allied powers: United Kingdom Soviet Union United States Republic of China and others Major Axis powers: Nazi Germany Italy Japan and others Commanders Winston Churchill Joseph Stalin Franklin Roosevelt Harry Truman Chiang Kai-Shek Adolf Hitler Benito Mussolini Hideki Tojo Casualties Military dead: 17,000,000 Civilian dead... Rocket fuel is a propellant that reacts with an oxidizing agent to produce thrust in a rocket. ... Titan II rockets launched 12 U.S. Gemini spacecraft in the 1960s. ... For other uses, please see Cold War (disambiguation). ...

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. For most of the 20th century, the U.S. Bureau of Mines (USBM) was the primary United States Government agency conducting scientific research and disseminating information on the extraction, processing, use, and conservation of mineral resources. ... Bushton is a city located in Rice County, Kansas. ... Nickname: The Yellow Rose of Texas, Helium Capital of the World, Rotor City USA Location within the state of Texas Coordinates: Country United States State Texas County Potter (and Randall) Mayor Debra McCartt Area    - City 233. ...

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.^[15][18] The resulting "Helium Privatization Act of 1996" ^[19] (Public Law 104–273) directed the United States Department of the Interior to start liquidating the reserve by 2005.^[20] Congress in Joint Session. ... The United States Department of the Interior (DOI) is a Cabinet department of the United States government that manages and conserves most federally-owned land. ...

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. General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless Atomic mass 14. ...

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 early 2000s, Algeria and Qatar were added as well. Algeria quickly became the second leading producer of helium. Through this time, both helium consumption and the costs of producing helium increased.

Occurrence and production

Natural abundance

Helium is the second most abundant element in the known Universe after hydrogen and constitutes 23% of the elemental mass of the universe. It is concentrated in stars, where it is formed from hydrogen by the nuclear fusion of the proton-proton chain reaction and 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. General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... Unsolved problems in physics: What causes anything to have mass? Mass is a property of a physical object that quantifies the amount of matter and energy it is equivalent to. ... The Pleiades, an open cluster of stars in the constellation of Taurus. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ... Overveiw of the proton-proton chain. ... This article does not cite its references or sources. ... According to the Big Bang, the universe emerged from an extremely dense and hot state (bottom). ... The deepest visible-light image of the cosmos, the Hubble Ultra Deep Field. ... In cosmology, Big Bang nucleosynthesis (or primordial nucleosynthesis) refers to the production of nuclei other than H-1, the normal, light hydrogen, during the early phases of the universe, shortly after the Big Bang. ...

In the Earth's atmosphere, the concentration of helium by volume is only 5.2 parts per million, largely because most helium in the Earth's atmosphere escapes into space due to its inertness and low mass. In the Earth's heterosphere, a part of the upper atmosphere, helium and other lighter gases are the most abundant elements. Layers of Atmosphere (NOAA) Air redirects here. ... Earths atmosphere is the layer of gases surrounding the planet Earth and retained by the Earths gravity. ...

Nearly all helium on Earth is a result of radioactive decay. The decay product is primarily found in minerals of uranium and thorium, including cleveites, pitchblende, carnotite, monazite and beryl, because they emit alpha particles, which consist of helium nuclei (He²⁺) to which electrons readily combine. In this way an estimated 3.4 litres of helium per year are generated per cubic kilometer of the Earth's crust. In the Earth's crust, the concentration of helium is 8 parts per billion. In seawater, the concentration is only 4 parts per trillion. There are also small amounts in mineral springs, volcanic gas, and meteoric iron. The greatest concentrations on the planet are in natural gas, from which most commercial helium is derived. Earth (IPA: , often referred to as the Earth, Terra, the World or Planet Earth) is the third planet in the solar system in terms of distance from the Sun, and the fifth largest. ... Radioactive decay is the set of various processes by which unstable atomic nuclei emit subatomic particles (radiation). ... In nuclear physics, a decay product, also known as a daughter product, is a nuclide resulting from the radioactive decay of a parent or precursor nuclide. ... General Name, Symbol, Number uranium, U, 92 Chemical series actinides Group, Period, Block n/a, 7, f Appearance silvery gray metallic; corrodes to a spalling black oxide coat in air Atomic mass 238. ... General Name, Symbol, Number thorium, Th, 90 Chemical series Actinides Group, Period, Block n/a, 7, f Appearance silvery white Atomic mass 232. ... Cleveite is a radioactive mineral containing uranium and found in Norway. ... Uraninite is a uranium-rich mineral with a composition that is largely UO2 (uranium oxide), but which also contains UO3 and oxides of lead, thorium, and rare earths. ... Carnotite is a potassium uranium vanadate mineral with chemical formula: K2(UO2)2(VO4)2·3H2O. The water content can vary and small amounts of calcium, barium, magnesium, iron, and sodium are often present. ... Monazite powder In geology, the mineral monazite is a reddish-brown phosphate containing rare earth metals and an important source of thorium, lanthanum, and cerium. ... Beryl var. ... An alpha particle is deflected by a magnetic field Alpha particles (named after the first letter in the Greek alphabet, α) are a highly ionizing form of particle radiation which have low penetration. ... A natural spring on Mackinac Island in Michigan. ... Volcano 1. ... Natural gas is a gaseous fossil fuel consisting primarily of methane. ...

Extraction

For large-scale use, helium is extracted by fractional distillation from natural gas, which contains up to 7% helium.^[21] Since helium has a lower boiling point than any other element, low temperature and high pressure are used to liquefy nearly all the other gases (mostly nitrogen and methane). The resulting crude helium gas is purified by successive exposures to lowering temperatures, in which almost all of the remaining nitrogen and other gases are precipitated out of the gaseous mixture. Activated charcoal is used as a final purification step, usually resulting in 99.995% pure, Grade-A, helium.^[22] The principal impurity in Grade-A helium is neon. Fractional distillation is the separation of a mixture into its component parts, or fractions, such as in separating chemical compounds by their boiling point by heating them to a temperature at which several fractions of the compound will evaporate. ... Natural gas is a gaseous fossil fuel consisting primarily of methane. ... General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless Atomic mass 14. ... Methane is a significant and plentiful fuel which is the principal component of natural gas. ... Activated carbon (also called activated charcoal) is the more general term which includes material mostly derived from charcoal. ... General Name, Symbol, Number neon, Ne, 10 Chemical series noble gases Group, Period, Block 18, 2, p Appearance colorless Atomic mass 20. ...

As of 2004, over one hundred and fifty million cubic metres of helium were extracted from natural gas or withdrawn from helium reserves, annually, with approximately 84% of production from the United States, 10% from Algeria, and most of the remainder from Canada, China, Poland, Qatar, and Russia. In the United States, most helium is produced in Kansas and Texas.^[23]

Diffusion of crude natural gas through special semi-permeable membranes and other barriers is another method to recover and purify helium. Helium can be synthesized by bombardment of lithium or boron with high-velocity protons, but this is not an economically viable method of production. Permeability has several meanings: In electromagnetism, permeability is the degree of magnetisation of a material in response to a magnetic field. ... General Name, Symbol, Number lithium, Li, 3 Chemical series alkali metals Group, Period, Block 1, 2, s Appearance silvery white/grey Atomic mass 6. ... General Name, Symbol, Number boron, B, 5 Chemical series metalloids Group, Period, Block 13, 2, p Appearance black/brown Atomic mass 10. ... Properties [1][2] In physics, the proton (Greek proton = first) is a subatomic particle with an electric charge of one positive fundamental unit (1. ...

Isotopes

Although there are eight known isotopes of helium, only helium-3 and helium-4 are stable. In the Earth's atmosphere, there is one He-3 atom for every million He-4 atoms.^[4] 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.^[24] 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. Isotopes are any of the several different forms of an element each having different atomic mass. ... Helium-3 is a non-radioactive and light isotope of helium. ... Helium-4 is a non-radioactive and light isotope of helium. ... This article needs to be cleaned up to conform to a higher standard of quality. ... The distribution of ionized hydrogen (known by astronomers as H II (aitch two) from old spectroscopic terminology) in the parts of the Galactic interstellar medium visible from the Earths northern hemisphere (from the Wisconsin H-Alpha Mapper Survey) In astronomy, the interstellar medium (or ISM) is the matter (interstellar... World geologic provinces Oceanic crust  0-20 Ma  20-65 Ma  >65 Ma Geologic provinces  Shield  Platform  Orogen  Basin  Large igneous province  Extended crust Geology (from Greek γη- (ge-, the earth) and λογος (logos, word, reason))[1] is the science and study of the solid matter of a celestial body, its composition...

The most common isotope, helium-4, is produced on Earth by alpha decay of heavier radioactive elements; the alpha particles that emerge are fully ionized helium-4 nuclei. Helium-4 is an unusually stable nucleus because its nucleons are arranged into complete shells. It was also formed in enormous quantities during Big Bang nucleosynthesis. Alpha decay is a form of radioactive decay in which an atomic nucleus ejects an alpha particle through the electromagnetic force and transforms into a nucleus with mass number 4 less and atomic number 2 less. ... An alpha particle is deflected by a magnetic field Alpha particles (named after the first letter in the Greek alphabet, α) are a highly ionizing form of particle radiation which have low penetration. ... In physics a nucleon is a collective name for two baryons: the neutron and the proton. ... In nuclear physics, the nuclear shell model is a model of the atomic nucleus. ... In cosmology, Big Bang nucleosynthesis (or primordial nucleosynthesis) refers to the production of nuclei other than H-1, the normal, light hydrogen, during the early phases of the universe, shortly after the Big Bang. ...

Equal mixtures of liquid helium-3 and helium-4 below 0.8 K will separate into two immiscible phases due to their dissimilarity (they follow different quantum statistics: helium-4 atoms are bosons while helium-3 atoms are fermions).^[25] Dilution refrigerators take advantage of the immiscibility of these two isotopes to achieve temperatures of a few millikelvins. There is only a trace amount of helium-3 on Earth, primarily present since the formation of the Earth, although some falls to Earth trapped in cosmic dust.^[26] Trace amounts are also produced by the beta decay of tritium.^[27] In stars, however, helium-3 is more abundant, a product of nuclear fusion. Extraplanetary material, such as lunar and asteroid regolith, have trace amounts of helium-3 from being bombarded by solar winds. Statistics of interacting identical particles (=when their wave functions overlap). ... In particle physics, bosons, named after Satyendra Nath Bose, are particles having integer spin. ... In particle physics, fermions are particles with half-integer spin. ... A dilution refrigerator is a cryogenic device first proposed by Heinz London. ... In nuclear physics, beta decay (sometimes called neutron decay) is a type of radioactive decay in which a beta particle (an electron or a positron) is emitted. ... Tritium (symbol T or 3H) is a radioactive isotope of hydrogen. ... The Pleiades, an open cluster of stars in the constellation of Taurus. ... The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ... Adjective lunar Bulk silicate composition (estimated wt%) SiO2 44. ... 253 Mathilde, a C-type asteroid. ... Regolith (Greek: blanket rock) is a layer of loose, heterogeneous material covering solid rock. ... The plasma in the solar wind meeting the heliopause For the British comic, see Solar Wind (comic). ...

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.^[26] Earth cutaway from core to exosphere. ...

It is possible to produce exotic helium isotopes, which rapidly decay into other substances. The shortest-lived isotope is helium-5 with a half-life of 7.6×10⁻²² second. Helium-6 decays by emitting a beta particle and has a half life of 0.8 second. Helium-7 also emits a beta particle as well as a gamma ray. Helium-7 and helium-8 are hyperfragments that are created in certain nuclear reactions.^[28] Exotic helium isotopes are the unstable isotopes of helium. ... Half-Life For a quantity subject to exponential decay, the half-life is the time required for the quantity to fall to half of its initial value. ... Alpha radiation consists of helium nuclei and is readily stopped by a sheet of paper. ... This article is about electromagnetic radiation. ... In nuclear physics, a nuclear reaction is a process in which two nuclei or nuclear particles collide, to produce different products than the initial products. ...

Precautions

The voice of a person who has inhaled helium temporarily sounds high-pitched. This is because the speed of sound in helium is nearly three times that in air. Because the fundamental frequency of a gas-filled cavity is proportional to the speed of sound in the gas, when helium is inhaled there is a corresponding increase in the resonant frequencies of the vocal tract.^[14] The speed of sound is a term used to describe the speed of sound waves passing through an elastic medium. ... The fundamental tone, often referred to simply as the fundamental, is the lowest frequency in a harmonic series. ... This article is about resonance in physics. ... The vocal tract is that cavity in animals and humans, where sound that is produced at the sound source (larynx in mammals; syrinx in birds) is filtered. ...

Although the vocal effect of inhaling helium may be amusing, it can be dangerous if done to excess since helium is a simple asphyxiant, thus it displaces oxygen needed for normal respiration. Death by asphyxiation will result within minutes if pure helium is breathed continuously. In Mammals (with the notable exception of seals) the breathing reflex is triggered by excess of 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. Asphyxia is a condition of severely deficient supply of oxygen to the body. ... General Name, Symbol, Number oxygen, O, 8 Chemical series Nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Atomic mass 15. ... Respiration is the process by which an organism obtains energy by reacting oxygen with glucose to give water, carbon dioxide and ATP (energy). ... Asphyxia is a condition of severely deficient supply of oxygen to the body. ... Orders Subclass Monotremata Monotremata Subclass Marsupialia Didelphimorphia Paucituberculata Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Subclass Placentalia Xenarthra Dermoptera Desmostylia Scandentia Primates Rodentia Lagomorpha Insectivora Chiroptera Pholidota Carnivora Perissodactyla Artiodactyla Cetacea Afrosoricida Macroscelidea Tubulidentata Hyracoidea Proboscidea Sirenia The mammals are the class of vertebrate animals primarily characterized by the presence of mammary... Families Odobenidae Otariidae Phocidae A Pacific walrus A leopard seal on Kerguelen Pinnipeds (fin-feet, lit. ... Carbon dioxide is a chemical compound composed of one carbon and two oxygen atoms. ... Air hunger is the sensation of the urge to breathe. ... Barotrauma is physical damage to body tissues caused by a difference in pressure between an air space inside or beside the body and the surrounding gas or liquid. ... The lungs flank the heart and great vessels in the chest cavity. ...

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.^[29] Trinomial name Homo sapiens sapiens Linnaeus, 1758 Humans, or human beings, are bipedal apes belonging to the mammalian species Homo sapiens (Latin for wise man or knowing man) under the family Hominidae (known as the great apes). ... Human blood smear: a - erythrocytes; b - neutrophil; c - eosinophil; d - lymphocyte. ... Heliox is a gas that is composed of a mixture of helium (He) and oxygen (O2). ... HPNS, High Pressure Nervous Syndrome or Helium Tremors is a diving disorder caused by using breathing gases that contain helium at depths in excess of 130 metres / 429 feet. ...

Containers of helium gas at 5 to 10 K should be handled as if they have liquid helium inside due to the rapid and significant thermal expansion that occurs when helium gas at less than 10 K is warmed to room temperature.^[2] In physics, thermal expansion is the tendency of matter to increase in volume or pressure when heated. ... To meet Wikipedias quality standards, this article may require cleanup. ...

References

March 31 is the 90th day of the year in the Gregorian Calendar (91st in Leap years), with 275 days remaining. ... 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ... April 1 is the 91st day of the year (92nd in leap years) in the Gregorian calendar, with 274 days remaining. ... 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ... September 19 is the 262nd day of the year (263rd in leap years). ... 2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ... April 4 is the 94th day of the year in the Gregorian calendar (95th in leap years). ... 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ... April 4 is the 94th day of the year in the Gregorian calendar (95th in leap years). ... 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ... January 1 is the first day of the calendar year in both the Julian and Gregorian calendars. ... 1983 (MCMLXXXIII) was a common year starting on Saturday of the Gregorian calendar. ... April 5 is the 95th day of the year in the Gregorian calendar (96th in leap years). ... 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ... April 5 is the 95th day of the year in the Gregorian calendar (96th in leap years). ... 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ... October 10 is the 283rd day of the year (284th in Leap years). ... For album titles with the same name, see 2002 (album). ...

Notes

October 10 is the 283rd day of the year (284th in Leap years). ... For album titles with the same name, see 2002 (album). ... March 25 is the 84th day of the year in the Gregorian calendar (85th in leap years). ... 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ... The American Chemical Society (ACS) is a learned society (professional association) based in the United States that supports scientific inquiry in the field of chemistry. ... 2006 (MMVI) is a common year starting on Sunday of the Gregorian calendar. ... May 17 is the 137th day of the year in the Gregorian Calendar (138th in leap years). ... The United States Geological Survey (USGS) is a scientific agency of the United States government. ... 2006 (MMVI) is a common year starting on Sunday of the Gregorian calendar. ... May 22 is the 142nd day of the year in the Gregorian calendar (143rd in leap years). ...

External links

Wikimedia Commons has media related to: Helium

Look up helium in
Wiktionary, the free dictionary.

General

• WebElements: Helium
• It's Elemental – Helium
• Photos and applications of Helium
• Fluidmech.net about liquid Helium-II and low temperature phase diagram

More detail

• Helium at the Helsinki University of Technology; includes pressure-temperature phase diagrams for helium-3 and helium-4.
• Lancaster University, Ultra Low Temperature Physics - includes a summary of some low temperature techniques.

Miscellaneous

• Phase diagram of helium, showing lambda line
• Helium Safety regarding inhalation
• Physics in Speech with audio samples that demonstrate the unchanged voice pitch
• Article about Helium and other noble gases

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For the mathematical constant see: E (mathematical constant). ... The color of food is considered important in its enjoyment. ... A preservative is a natural or synthetic chemical that is added to products such as foods, pharmaceuticals, paints, biological samples, etc. ... This article or section is in need of attention from an expert on the subject. ... Acidity regulators, or pH control agents, are food additives added to change or maintain pH (acidity or basicity). ... Thickening agents, or thickeners, are substances which, when added to the mixture, increase its viscosity without substantially modifying its other properties, like eg. ... The tail of a Lufthansa airliner (Airbus A319) in flight, showing the horizontal stabilizer Mathematics: see Group action. ... An emulsion is a mixture of two immiscible substances. ... . The initial letter is shown capitalized due to technical restrictions. ... Anticaking agents are used in such things as table salt to keep the product from forming lumps, making it better for packaging, transport and for the consumer. ... Flavour enhancers are commonly added to commercially produced food products (eg. ... Wax has traditionally referred to a substance that is secreted by bees (beeswax) and used by them in constructing their honeycombs. ... Glazing agents, or polishing agents, are food additives providing shiny appeareance or protective coating to foods. ... Flour treatment agents (also called improving agents) are food additives added to flour in order to improve its properties. ... A packaging gas is a gas used for packaging of sensitive materials in modified atmosphere. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... A foaming agent is a material that will decompose to release a gas under certain conditions (typically high temperature), which can be used to turn a liquid into a foam. ... General Name, Symbol, Number argon, Ar, 18 Chemical series noble gases Group, Period, Block 18, 3, p Appearance colorless Atomic mass 39. ... Disclaimer and references Dichlorodifluoromethane (R-12), usually sold under the brand name Freon-12, is a chlorofluorocarbon halomethane used as a refrigerant and aerosol spray propellant until its manufacture was discontinued in 1995, due to concerns about damage to the ozone layer. ... General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless Atomic mass 14. ... R-phrases S-phrases Supplementary data page Structure and properties n, εr, etc. ... Butane, also called n-butane, is the unbranched alkane with four carbon atoms, CH3CH2CH2CH3. ... Butane is an alkane hydrocarbon with the molecular formula C4H10. ... Propane is a three-carbon alkane, normally a gas, but compressible to a liquid that is transportable. ... General Name, Symbol, Number oxygen, O, 8 Chemical series Nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Atomic mass 15. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ...