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For other uses of this term, see Helium (disambiguation).
2 hydrogen ← helium → lithium
-
↑
He
↓
Ne
General
Name, symbol, number helium, He, 2
Chemical series noble gases
Group, period, block 18, 1, s
Appearance colorless
Standard atomic weight 4.002602(2) g·mol−1
Electron configuration 1s2
Electrons per shell 2
Physical properties
Phase gas
Density (0 °C, 101. Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Lithium (ˈlɪθiəm is a Chemical element with the symbol Li and Atomic number 3 Neon (ˈniːɒn is the Chemical element that has the symbol Ne and Atomic number 10 This is a typical display of the periodic table of the elements and contains the symbol and Atomic number of each element Wikipedia talkFeatured lists for an explanation of this and other inclusion tags below -->This is a list of Chemical elements, sorted by name Wikipedia talkFeatured lists for an explanation of this and other inclusion tags below -->This is a list of chemical elements by symbol, including the A table of Chemical elements ordered by Atomic number and color coded according to type of element In Chemistry a group, also known as a family, is a vertical column in the Periodic table of the Chemical elements There are 18 groups in History Noble gas is translated from the German noun de ''Edelgas'' first used in 1898 by Hugo Erdmann to indicate their extremely low level of reactivity In Chemistry a group, also known as a family, is a vertical column in the Periodic table of the Chemical elements There are 18 groups in In the Periodic table of the elements, a period is a horizontal row of the table A block of the Periodic table of elements is a set of adjacent groups The respective highest-energy electrons in each element in a block belong to the same Atomic History Noble gas is translated from the German noun de ''Edelgas'' first used in 1898 by Hugo Erdmann to indicate their extremely low level of reactivity A period 1 element is one of the Chemical elements in the first row (or period) of the periodic table of the chemical elements. See also Electron configuration The atomic mass (ma is the Mass of an atom most often expressed in unified atomic mass units The atomic mass may be considered to be the total mass To help compare different orders of magnitude, the following list describes various Mass levels between 10&minus36&thinsp kg and 1053&thinspkg Molar mass, symbol M, is the Mass of one mole of a substance ( Chemical element or Chemical compound) In Atomic physics and Quantum chemistry, electron configuration is the arrangement of Electrons in an Atom, Molecule, or other The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J An electron shell may be crudely thought of as an Orbit followed by Electrons around an Atom nucleus. 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 This page is about the physical properties of gas as a state of matter The density of a material is defined as its Mass per unit Volume: \rho = \frac{m}{V} Different materials usually have different 325 kPa)
0. 1786 g/L
Melting point (at 2. The melting point of a solid is the temperature range at which it changes state from solid to Liquid. 5 MPa) 0. 95 K
(−272. The kelvin (symbol K) is a unit increment of Temperature and is one of the seven SI base units The Kelvin scale is a thermodynamic 2 °C, −458. The Celsius Temperature scale was previously known as the centigrade scale. 0 °F)
Boiling point 4. Fahrenheit is a temperature scale named after Daniel Gabriel Fahrenheit (1686–1736 a German Physicist who proposed it in 1724 The boiling point of a liquid is the temperature at which the Vapor pressure of the liquid equals the environmental pressure surrounding the liquid 22 K
(−268. The kelvin (symbol K) is a unit increment of Temperature and is one of the seven SI base units The Kelvin scale is a thermodynamic 93 °C, −452. The Celsius Temperature scale was previously known as the centigrade scale. 07 °F)
Critical point 5. Fahrenheit is a temperature scale named after Daniel Gabriel Fahrenheit (1686–1736 a German Physicist who proposed it in 1724 In Physical chemistry, Thermodynamics, Chemistry and Condensed matter physics, a critical point, also called a critical state 19 K, 0. The kelvin (symbol K) is a unit increment of Temperature and is one of the seven SI base units The Kelvin scale is a thermodynamic 227 MPa
Heat of fusion 0. The standard Enthalpy of fusion (symbol \Delta{}H_{fus} also known as the heat of fusion or specific melting heat, is the amount of 0138 kJ·mol−1
Heat of vaporization 0. The joule per mole (symbol J·mol-1 is an SI derived unit of energy per amount of material The enthalpy of vaporization, (symbol \Delta{}_{v}H also known as the heat of vaporization or heat of evaporation, is the Energy required 0829 kJ·mol−1
Specific heat capacity (25 °C) 20. The joule per mole (symbol J·mol-1 is an SI derived unit of energy per amount of material Specific heat capacity, also known simply as specific heat, is the measure of the heat energy required to increase the Temperature of a unit quantity 786 J·mol−1·K−1
Vapor pressure (defined by ITS-90)
P/Pa 1 10 100 1 k 10 k 100 k
at T/K     1. Vapor pressure (also known as equilibrium vapor pressure or saturation vapor pressure) is the Pressure of a Vapor in equilibrium The International Temperature Scale of 1990 ( ITS-90) is an equipment calibration standard for making measurements on the Kelvin and 23 1. 67 2. 48 4. 21
Atomic properties
Crystal structure hexagonal close-packed
Electronegativity no data (Pauling scale)
Ionization energies 1st: 2372. In Mineralogy and Crystallography, a crystal structure is a unique arrangement of Atoms in a Crystal. " Electronegativity " is the opposite of " Electropositivity," which describes an element's ability to donate electrons The ionization potential, ionization energy or EI of an Atom or Molecule is the Energy required to remove an Electron 3 kJ·mol−1
2nd: 5250. The joule per mole (symbol J·mol-1 is an SI derived unit of energy per amount of material 5 kJ·mol−1
Atomic radius (calc. ) 31 pm
Covalent radius 32 pm
Van der Waals radius 140 pm
Miscellaneous
Thermal conductivity (300 K) 0. The covalent radius, r cov is a measure of the size of Atom which forms part of a Covalent bond. Van der Waals Volume The van der Waals volume, V, also called the atomic volume or molecular volume, is the atomic property most directly In Physics, thermal conductivity, k is the property of a material that indicates its ability to conduct Heat. 1513  W·m−1·K−1
Thermal expansion (25 °C) { µm·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. When the Temperature of a substance changes the energy that is stored in the Intermolecular bonds between atoms changes CAS registry numbers are unique numerical identifiers for Chemical compounds Polymers biological sequences mixtures and Alloys They are also referred to Although there are eight known Isotopes of Helium ( He) (standard atomic mass 4 Isotopes (Greek isos = "equal" tópos = "site place" are any of the different types of atoms ( Nuclides In Chemistry, natural abundance (NA refers to the abundance Isotopes of a Chemical element as naturally found on a planet Half-Life (computer-game page here It's already listed in the disambiguation page Radioactive decay is the process in which an unstable Atomic nucleus loses energy by emitting ionizing particles and Radiation. The decay energy is the Energy released by a Nuclear decay. The energy difference of the Reactants is often written as Q: where Q In Nuclear physics, a decay product, also known as a daughter product, daughter isotope or daughter nuclide, is a Nuclide This article is about the elemental isotope For the record label Helium 3 see Muse or A&E Records. 000137%* 3He is stable with 1 neutrons
4He 99. Stable isotopes are chemical isotopes that are not Radioactive (to current knowledge This article is a discussion of neutrons in general For the specific case of a neutron found outside the nucleus see Free neutron. Helium-4 ( or) is a non- Radioactive and light Isotope of Helium. 999863%* 4He is stable with 2 neutrons
*Atmospheric value, abundance may differ elsewhere. Stable isotopes are chemical isotopes that are not Radioactive (to current knowledge This article is a discussion of neutrons in general For the specific case of a neutron found outside the nucleus see Free neutron.
References
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Helium (He) is a colorless, odorless, tasteless, non-toxic, inert monatomic chemical element that heads the noble gas series in the periodic table and whose atomic number is 2. Recommended values for many properties of the elements together with various references are collected on these data pages 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. A chemical element is a type of Atom that is distinguished by its Atomic number; that is by the number of Protons in its nucleus. History Noble gas is translated from the German noun de ''Edelgas'' first used in 1898 by Hugo Erdmann to indicate their extremely low level of reactivity The periodic table of the chemical elements is a tabular method of displaying the Chemical elements Although precursors to this table exist its invention is See also List of elements by atomic number In Chemistry and Physics, the atomic number (also known as the proton Its boiling and melting points are the lowest among the elements and it exists only as a gas except in extreme conditions. The boiling point of a liquid is the temperature at which the Vapor pressure of the liquid equals the environmental pressure surrounding the liquid The melting point of a solid is the temperature range at which it changes state from solid to Liquid. This page is about the physical properties of gas as a state of matter

Helium was discovered in 1868 by French astronomer Pierre Janssen, who first detected the substance as an unknown yellow spectral line signature in light from a solar eclipse. Pierre Jules César Janssen ( February 22, 1824 &ndash December 23, 1907) was a French astronomer who along with the English Spectroscopy was originally the study of the interaction between Radiation and Matter as a function of Wavelength (λ A solar eclipse occurs when the Moon passes between the Sun and the Earth so that the Sun is wholly or partially obscured In 1903, large reserves of helium were found in the natural gas fields of the United States, which is by far the largest supplier of the gas. Oil and Natural gas are produced by the same geological process anaerobic Decay of Organic matter deep under the Earth's surface The United States of America —commonly referred to as the The substance is used in cryogenics, in deep-sea breathing systems, to cool superconducting magnets, in helium dating, for inflating balloons, for providing lift in airships and as a protective gas for many industrial uses (such as arc welding and growing silicon wafers). Cryogenics is often used incorrectly to refer to Cryonics, cryopreserving humans or animals A superconducting magnet is an Electromagnet that is built using superconducting coils Helium dating is a method of determining the age of a substance using the decay of radioactive isotopes A balloon is a flexible bag filled with a type of Gas, such as Helium, Hydrogen, Nitrous oxide or air. Terminology In some countries airships are also known as dirigibles from the French (fr ''diriger'' to direct plus -ible) meaning "directable" Arc welding uses a Welding power supply to create an Electric arc between an electrode and the base material to melt the metals at the welding point Silicon (ˈsɪlɪkən or /ˈsɪlɪkɒn/ silicium is the Chemical element that has the symbol Si and Atomic number 14 A much less serious use is to temporarily change the timbre and quality of one's voice by inhaling a small volume of the gas. The volume of any solid plasma vacuum or theoretical object is how much three- Dimensional space it occupies often quantified numerically The behavior of liquid helium-4's two fluid phases, helium I and helium II, is important to researchers studying quantum mechanics (in particular the phenomenon of superfluidity) and to those looking at the effects that temperatures near absolute zero have on matter (such as superconductivity). Quantum mechanics is the study of mechanical systems whose dimensions are close to the Atomic scale such as Molecules Atoms Electrons Superfluidity is a phase of matter or description of Heat capacity in which unusual effects are observed when Liquids, typically of Helium-4 Absolute zero is the point at which molecules do not move (relative to the rest of the body more than they are required to by a quantum mechanical effect called Zero-point Matter is commonly defined as being anything that has mass and that takes up space. Superconductivity is a phenomenon occurring in certain Materials generally at very low Temperatures characterized by exactly zero electrical resistance

Helium is the second most abundant and second lightest element in the known universe and is one of the elements thought to have been created in the Big Bang. In Chemistry, natural abundance (NA refers to the abundance Isotopes of a Chemical element as naturally found on a planet The Universe is defined as everything that Physically Exists: the entirety of Space and Time, all forms of Matter, Energy The Big Bang is the cosmological model of the Universe that is best supported by all lines of scientific evidence and Observation. Almost all new helium is created as a result of the nuclear fusion of hydrogen in stars. In Physics and Nuclear chemistry, nuclear fusion is the process by which multiple- like charged atomic nuclei join together to form a heavier nucleus A star is a massive luminous ball of plasma. The nearest star to Earth is the Sun, which is the source of most of the Energy on Earth On Earth, Helium is relatively rare and is naturally created by the radioactive decay of much heavier elements, as the alpha particles emitted by some radioactive elements are helium nuclei by another name. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 Radioactive decay is the process in which an unstable Atomic nucleus loses energy by emitting ionizing particles and Radiation. Alpha particles (named after and denoted by the first letter in the Greek alphabet, α consist of two Protons and two Neutrons bound together into a The nucleus of an Atom is the very dense region consisting of Nucleons ( Protons and Neutrons, at the center of an atom After its creation, some helium was trapped with natural gas in concentrations up to seven percent by volume, from which it is extracted commercially by a low-temperature separation process called fractional distillation. Natural gas is a Gaseous Fossil fuel consisting primarily of Methane but including significant quantities of Ethane, Propane, 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

Contents

Notable characteristics

Gas and plasma phases

Helium is the least reactive member of the noble gas elements, and thus also the least reactive of all elements; it is inert and monatomic in virtually all conditions. History Noble gas is translated from the German noun de ''Edelgas'' first used in 1898 by Hugo Erdmann to indicate their extremely low level of reactivity 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. Due to helium's relatively low molar (atomic) mass, in the gas phase its thermal conductivity, specific heat, and sound conduction velocity are all greater than for any other gas except hydrogen. In Physics, thermal conductivity, k is the property of a material that indicates its ability to conduct Heat. Specific heat capacity, also known simply as specific heat, is the measure of the heat energy required to increase the Temperature of a unit quantity Sound is a vibration that travels through an elastic medium as a Wave. Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 For similar reasons, and also due to the small size of helium atoms, helium's diffusion rate through solids is three times that of air and around 65% that of hydrogen. Diffusion is the net movement of particles (typically molecules from an area of high concentration to an area of low concentration by uncoordinated random movement A solid' object is in the States of matter characterized by resistance to Deformation and changes of Volume. [1]

Helium is less water soluble than any other gas known[2] and helium's index of refraction is closer to unity than that of any other gas. Solubility is the characteristic Physical property referring to the ability of a given substance the Solute, to dissolve in a Solvent. The refractive index (or index of Refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves is reduced inside the medium Helium has a negative Joule-Thomson coefficient at normal ambient temperatures, meaning it heats up when allowed to freely expand. In Physics, the Joule–Thomson effect or Joule–Kelvin effect describes the Temperature change of a gas or liquid when it is forced through a Valve Only below its Joule-Thomson inversion temperature (of about 40 K at 1 atmosphere) does it cool upon free expansion. In Physics, the Joule–Thomson effect or Joule–Kelvin effect describes the Temperature change of a gas or liquid when it is forced through a Valve The kelvin (symbol K) is a unit increment of Temperature and is one of the seven SI base units The Kelvin scale is a thermodynamic Once precooled below this temperature, helium can be liquefied through expansion cooling.

Helium discharge tube shaped like the element's atomic symbol
Helium discharge tube shaped like the element's atomic symbol

Throughout the universe, helium is found mostly in a plasma state whose properties are quite different from atomic helium. In Physics and Chemistry, plasma is an Ionized Gas, in which a certain proportion of Electrons are free rather than being bound In 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. The solar wind is a Stream of charged particles&mdasha plasma &mdashthat are ejected from the upper atmosphere of the Sun. A magnetosphere' is a highly magnetized region around and possessed by an Astronomical object. A Birkeland current is a specific magnetic field aligned current in the Earth’s Magnetosphere which flows from the Magnetotail towards the Earth on the dawn side

Solid and liquid phases

Main article: Liquid helium

Helium solidifies only under great pressure. Helium exists in Liquid form only at very low Temperatures The Boiling point and critical point depend on the Isotope The resulting colorless, almost invisible solid is highly compressible; applying pressure in a laboratory can decrease its volume by more than 30%. A solid' object is in the States of matter characterized by resistance to Deformation and changes of Volume. In Thermodynamics and Fluid mechanics, compressibility is a measure of the relative volume change of a Fluid or Solid as a response [3] With a bulk modulus on the order of 5×107 Pa[4] 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. Absolute zero is the point at which molecules do not move (relative to the rest of the body more than they are required to by a quantum mechanical effect called Zero-point This is a direct effect of quantum mechanics: specifically, the zero point energy of the system is too high to allow freezing. In Physics, the zero-point energy is the lowest possible Energy that a Quantum mechanical Physical system may possess and is the energy of the Solid helium requires a temperature of 1–1. 5 K (about −272 °C or −457 °F) and about 25 bar (2. 5 MPa) of pressure. [5] It is often hard to distinguish solid from liquid helium since the refractive index of the two phases are nearly the same. The refractive index (or index of Refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves is reduced inside the medium The solid has a sharp melting point and has a crystalline structure. The melting point of a solid is the temperature range at which it changes state from solid to Liquid. In Materials science, a crystal is a Solid in which the constituent Atoms Molecules or Ions are packed in a regularly ordered repeating

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. [6]

Helium I state

Below its boiling point of 4. The boiling point of a liquid is the temperature at which the Vapor pressure of the liquid equals the environmental pressure surrounding the liquid 22 kelvin and above the lambda point of 2. The kelvin (symbol K) is a unit increment of Temperature and is one of the seven SI base units The Kelvin scale is a thermodynamic The Lambda point is the Temperature (approximately 217 K) below which normal fluid Helium (helium I transitions to Superfluid helium II 1768 kelvin, the isotope helium-4 exists in a normal colorless liquid state, called helium I. Isotopes (Greek isos = "equal" tópos = "site place" are any of the different types of atoms ( Nuclides Liquid is one of the principal States of matter. A liquid is a Fluid that has the particles loose and can freely form a distinct surface at the boundaries of Like other cryogenic liquids, helium I boils when it is heated. Cryogenics is often used incorrectly to refer to Cryonics, cryopreserving humans or animals It also contracts when its temperature is lowered until it reaches the lambda point, when it stops boiling and suddenly expands. The Lambda point is the Temperature (approximately 217 K) below which normal fluid Helium (helium I transitions to Superfluid helium II 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 index of refraction of 1. The refractive index (or index of Refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves is reduced inside the medium 026 which makes its surface so hard to see that floats of styrofoam are often used to show where the surface is. Styrofoam is a trademark for polystyrene Thermal insulation, a material manufactured by Dow Chemical Company. [7] This colorless liquid has a very low viscosity and a density one-eighth that of water, which is only one-fourth the value expected from classical physics. Viscosity is a measure of the resistance of a Fluid which is being deformed by either Shear stress or Extensional stress. The density of a material is defined as its Mass per unit Volume: \rho = \frac{m}{V} Different materials usually have different [7] 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. Quantum mechanics is the study of mechanical systems whose dimensions are close to the Atomic scale such as Molecules Atoms Electrons This may be an effect of its boiling point being so close to absolute zero, preventing random molecular motion (heat) from masking the atomic properties. In Physics, heat, symbolized by Q, is Energy transferred from one body or system to another due to a difference in Temperature [7]

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. In Physics, thermal conductivity, k is the property of a material that indicates its ability to conduct Heat. Evaporation is the process by which Molecules in a Liquid state (e 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. Superfluidity is a phase of matter or description of Heat capacity in which unusual effects are observed when Liquids, typically of Helium-4

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 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. A Rollin film, named after Bernard V Rollin, is a 30 nm -thick liquid film of Helium in the helium II state

Helium II is a superfluid, a quantum-mechanical state of matter with strange properties. Superfluidity is a phase of matter or description of Heat capacity in which unusual effects are observed when Liquids, typically of Helium-4 For example, when it flows through even capillaries of 10−7 to 10−8 m width it has no measurable viscosity. Viscosity is a measure of the resistance of a Fluid which is being deformed by either Shear stress or Extensional stress. 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. In Quantum mechanics, a stationary state is an Eigenstate of a Hamiltonian, or in other words a state of definite energy [8]

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. Gravitation is a natural Phenomenon by which objects with Mass attract one another 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. A nanometre ( American spelling: nanometer, symbol nm) ( Greek: νάνος nanos dwarf; μετρώ metrό count) is a This film is called a Rollin film and is named after the man who first characterized this trait, Bernard V. A Rollin film, named after Bernard V Rollin, is a 30 nm -thick liquid film of Helium in the helium II state Rollin. [9][10] 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. Waves propagating across a Rollin film are governed by the same equation as gravity waves in shallow water, but rather than gravity, the restoring force is the Van der Waals force. In Fluid dynamics, gravity waves are waves generated in a Fluid medium or at the interface between two media (e The Van der Waals equation is an Equation of state that can be derived from a special form of the potential between a pair of molecules (hard-sphere repulsion [11] 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. Sintering is a method for making objects from powder, by heating the material (below its Melting point - solid state sintering until its particles adhere 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. [12]

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. Copper (ˈkɒpɚ is a Chemical element with the symbol Cu (cuprum and Atomic number 29 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. In Solids the valence band is the highest range of Electron energies where electrons are normally present at Absolute zero. 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. In thermal physics, heat transfer is the passage of Thermal energy from a hot to a colder body The wave equation is an important second-order linear Partial differential equation that describes the propagation of a variety of Waves such as Sound waves 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. Second sound is a Quantum mechanical phenomenon in which Heat transfer occurs by wave -like motion rather than by the more usual mechanism of Diffusion [9]

Applications

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

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. Terminology In some countries airships are also known as dirigibles from the French (fr ''diriger'' to direct plus -ible) meaning "directable" The Goodyear Blimp is the collective name for a fleet of blimps operated by Goodyear Tire and Rubber Company for Advertising purposes and for use as a Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 The boiling point of a liquid is the temperature at which the Vapor pressure of the liquid equals the environmental pressure surrounding the liquid The density of a material is defined as its Mass per unit Volume: \rho = \frac{m}{V} Different materials usually have different Solubility is the characteristic Physical property referring to the ability of a given substance the Solute, to dissolve in a Solvent. In Physics, thermal conductivity, k is the 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 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.

History

Scientific discoveries

Evidence of helium was first detected on August 18, 1868 as a bright yellow line with a wavelength of 587. Events 293 BC - The oldest known Roman temple to Venus is founded starting the institution of Vinalia Rustica. Year 1868 ( MDCCCLXVIII) was a Leap year starting on Wednesday (link will display the full calendar of the Gregorian Calendar (or a Leap In Physics wavelength is the distance between repeating units of a propagating Wave of a given Frequency. 49 nanometres in the spectrum of the chromosphere of the Sun, by French astronomer Pierre Janssen during a total solar eclipse in Guntur, India. An element's 'emission spectrum' is the relative intensity of Electromagnetic radiation of each Frequency it emits when it is Heated (or more generally when The chromosphere (literally "colour sphere" is a thin layer of the Sun 's atmosphere just above the Photosphere, roughly 10000 kilometres deep The Sun (Sol is the Star at the center of the Solar System. Pierre Jules César Janssen ( February 22, 1824 &ndash December 23, 1907) was a French astronomer who along with the English A solar eclipse occurs when the Moon passes between the Sun and the Earth so that the Sun is wholly or partially obscured WikipediaWikiProject Indian cities for details --> Guntur ( Telugu: గుంటూరు Urdu: گنٹور, Hindi: गुंटूर India, officially the Republic of India (भारत गणराज्य inc-Latn Bhārat Gaṇarājya; see also other Indian languages) is a country This line was initially assumed to be sodium. Sodium (ˈsoʊdiəm is an element which has the symbol Na( Latin natrium, from Arabic natrun) atomic number 11 atomic mass 22 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,[15] and concluded that it was caused by an element in the Sun unknown on Earth. Sir Joseph Norman Lockyer, FRS ( May 17, 1836 &ndash August 16, 1920) was an English scientist and astronomer In Physics and Optics, the Fraunhofer lines are a set of Spectral lines named for the German physicist Joseph von Fraunhofer ( 1787 He and English chemist Edward Frankland named the element with the Greek word for the Sun, ἥλιος (helios)[16]

On 26 March 1895 British chemist William Ramsay isolated helium on Earth by treating the mineral cleveite (a variety of uraninite with at least 10% rare earth elements) with mineral acids. Sir Edward Frankland, KCB, FRS ( January 18, 1825 &ndash August 9, 1899) was a Chemist, one of the foremost Events 1026 - Pope John XIX crowns Conrad II as Holy Roman Emperor. Year 1895 ( MDCCCXCV) was a Common year starting on Tuesday (link will display full calendar of the Gregorian calendar (or a Common year Sir William Ramsay (2 October 1852 &ndash 23 July 1916 was a Scottish chemist who discovered the Noble gases and received the Nobel Prize in Cleveite is a radioactive Mineral containing Uranium and found in Norway. Rare earth elements and rare earth metals are according to IUPAC, the collection of seventeen Chemical elements in the Periodic table, namely In Computer science, ACID ( Atomicity Consistency Isolation Durability) is a set of properties that guarantee that Database transactions are 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. This article pertains to the chemical element For other uses see Argon (disambiguation. Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Sulfuric (or sulphuric acid, H 2 S[[oxygen O]]4 is a strong Mineral acid. [17][18][19][20][17] These samples were identified as helium by Lockyer and British physicist William Crookes. Sir William Crookes, OM, FRS (17 June 1832 – 4 April 1919 was an English Chemist and Physicist. 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. Per Teodor Cleve ( Stockholm February 10, 1840 &ndash Uppsala June 18, 1905) was a Swedish Chemist Nils Abraham Langlet ( July 9 1868 - March 30 1936; known by his second given name was a Swedish chemist. Uppsala ˈɵpˌsɑːla (older spelling Upsala) is the capital of Uppsala County ( Uppsala län) and the fourth largest city of The atomic mass (ma is the Mass of an atom most often expressed in unified atomic mass units The atomic mass may be considered to be the total mass [21] 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. [22]

In 1907, Ernest Rutherford and Thomas Royds demonstrated that alpha particles are helium nuclei, by allowing the particles to penetrate the thin glass wall of a evacuated tube, then creating a discharge in the tube to study the spectra of the new gas inside. Ernest Rutherford 1st Baron Rutherford of Nelson, OM, PC, FRS (30 August 1871 – 19 October 1937 was a New Zealand Physicist Alpha particles (named after and denoted by the first letter in the Greek alphabet, α consist of two Protons and two Neutrons bound together into a The nucleus of an Atom is the very dense region consisting of Nucleons ( Protons and Neutrons, at the center of an atom In 1908, helium was first liquefied by Dutch physicist Heike Kamerlingh Onnes by cooling the gas to less than one kelvin. Heike Kamerlingh Onnes ( September 21, 1853 &ndash February 21, 1926) was a Dutch Physicist. The kelvin (symbol K) is a unit increment of Temperature and is one of the seven SI base units The Kelvin scale is a thermodynamic 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. In Thermodynamics, the triple point of a substance is the Temperature and Pressure at which three phases (for example Gas, Liquid It was first solidified in 1926 by his student Willem Hendrik Keesom by subjecting helium to 25 atmospheres of pressure. Willem Hendrik Keesom ( June 21, 1876, Texel &ndash March 24 1956, Leiden) was a Dutch Physicist The Standard atmosphere is an international reference pressure defined as 101325 Pa and formerly used as unit of Pressure (symbol atm

In 1938, Russian physicist Pyotr Leonidovich Kapitsa discovered that helium-4 (a boson) has almost no viscosity at temperatures near absolute zero, a phenomenon now called superfluidity. Pyotr Leonidovich Kapitsa ( Russian Пётр Леонидович Капица ( July 9, 1894 &ndash April 8, 1984) was an innovative Helium-4 ( or) is a non- Radioactive and light Isotope of Helium. In Particle physics, bosons are particles which obey Bose-Einstein statistics; they are named after Satyendra Nath Bose and Albert Einstein Viscosity is a measure of the resistance of a Fluid which is being deformed by either Shear stress or Extensional stress. Absolute zero is the point at which molecules do not move (relative to the rest of the body more than they are required to by a quantum mechanical effect called Zero-point Superfluidity is a phase of matter or description of Heat capacity in which unusual effects are observed when Liquids, typically of Helium-4 This phenomenon is related to Bose-Einstein condensation. A Bose–Einstein condensate (BEC is a State of matter of Bosons confined in an external Potential and cooled to Temperatures very near to In 1972, the same phenomenon was observed in helium-3, but at temperatures much closer to absolute zero, by American physicists Douglas D. Osheroff, David M. Lee, and Robert C. Richardson. This article is about the elemental isotope For the record label Helium 3 see Muse or A&E Records. Absolute zero is the point at which molecules do not move (relative to the rest of the body more than they are required to by a quantum mechanical effect called Zero-point Douglas Dean Osheroff (born August 1, 1945) is an American physicist David Morris Lee (born January 20, 1931) is a physicist whose work on low-temperature Helium-3 won him the Nobel Prize in 1996 The phenomenon in helium-3 is thought to be related to pairing of helium-3 fermions to make bosons, in analogy to Cooper pairs of electrons producing superconductivity. In Particle physics, fermions are particles which obey Fermi-Dirac statistics; they are named after Enrico Fermi. In Particle physics, bosons are particles which obey Bose-Einstein statistics; they are named after Satyendra Nath Bose and Albert Einstein In Condensed matter physics, a Cooper pair is the name given to electrons that are bound together at low temperatures in a certain manner first described in 1956 by Superconductivity is a phenomenon occurring in certain Materials generally at very low Temperatures characterized by exactly zero electrical resistance

Extraction and use

After an oil drilling operation in 1903 in Dexter, Kansas, United States 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. Dexter is a city in Cowley County, Kansas, United States. The population was 364 at the 2000 census. Erasmus Haworth (1855–1932 was an American Geologist. Born on a farm near Indianola Iowa, he graduated from the University of Kansas with a bachelor Hamilton Perkins Cady, ( May 2, 1874 - May 26, 1943) was an American Chemist who in 1907 in collaboration with David [23] With further analysis, Cady and McFarland discovered that 1. 84% of the gas sample was helium. [24] 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. The United States of America —commonly referred to as the Following a suggestion by Sir Richard Threlfall, the United States Navy sponsored three small experimental helium production plants during World War I. Sir Richard Threlfall ( August 14 1861 - July 10 1932) was an English chemist and engineer he established the School of Physics at the University World War I (abbreviated WWI; also known as the First World War, the Great War, and the War to End All The goal was to supply barrage balloons with the non-flammable lifting gas. A barrage balloon is a large balloon tethered with metal cables used to defend against low-level attack by aircraft by damaging the aircraft on collision with the cables A total of 200 thousand cubic feet (5,700 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. [17] Some of this gas was used in the world's first helium-filled airship, the U. Terminology In some countries airships are also known as dirigibles from the French (fr ''diriger'' to direct plus -ible) meaning "directable" 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. Hampton Roads is the name of both a body of water and the region of land areas which surround it in southeastern Virginia in the USA. Bolling Air Force Base is a United States Air Force base in Southwest Washington D Washington DC ( formally the District of Columbia and commonly referred to as Washington, the District, or simply D Events 800 - Charlemagne judges the accusations against Pope Leo III in the Vatican Year 1921 ( MCMXXI) was a Common year starting on Saturday (link will display full 1921 calendar of the Gregorian calendar [25]

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. Welding is a fabrication process that joins materials usually Metals or Thermoplastics by causing coalescence. Helium was also vital in the atomic bomb Manhattan Project. The World War II Manhattan Project developed the first Nuclear weapon (atomic bomb

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. The federal government of the United States is the central United States Governmental body established by the United States Constitution. The National Helium Reserve, also known as the Federal Helium Reserve, is a strategic reserve of the United States holding over a billion cubic feet of Helium Terminology In some countries airships are also known as dirigibles from the French (fr ''diriger'' to direct plus -ible) meaning "directable" War is an international relations Dispute, characterized by organized Violence between National Military units Due to a US military embargo against Germany that restricted helium supplies, the Hindenburg was forced to use hydrogen as the lift gas. WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Helium use following World War II was depressed but the reserve was expanded in the 1950s to ensure a supply of liquid helium as a coolant to create oxygen/hydrogen rocket fuel (among other uses) during the Space Race and Cold War. World War II, or the Second World War, (often abbreviated WWII) was a global military conflict which involved a majority of the world's nations, including Rocket propellant is mass that is stored usually in some form of Propellant tank prior to being used as the propulsive mass that is ejected from a rocket engine in the form The Space Race was a competition of space exploration between the Soviet Union and the United States, which lasted roughly from 1957 to 1975 Cold War is the state of conflict tension and competition that existed between the United States and the Soviet Union (USSR and their respective allies from the 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 most of the 20th century the US Bureau of Mines (USBM was the primary United States Government agency conducting scientific research and disseminating information on 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. Bushton is a city in Rice County, Kansas, United States. The population was 314 at the 2000 census. 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. The United States Congress is the bicameral Legislature of the federal government of the United States of America, consisting of two houses [23][26] The resulting "Helium Privatization Act of 1996"[27] (Public Law 104–273) directed the United States Department of the Interior to start liquidating the reserve by 2005. The United States Department of the Interior ( DOI) is a Cabinet department of the United States government that manages and conserves most federally [28]

Helium produced before 1945 was about 98% pure (2% nitrogen), which was adequate for airships. Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 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. Country to "Dominion of Canada" or "Canadian Federation" or anything else please read the Talk Page Poland (Polska officially the Republic of Poland Russia (Россия Rossiya) or the Russian Federation ( Rossiyskaya Federatsiya) is a transcontinental Country extending In the mid-1990s, A new plant in Arzew, Algeria producing 600 million cubic feet (1. 7×107 m3) began operation, 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 hydrogen and constitutes 23% of the elemental mass of the universe. Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Mass is a fundamental concept in Physics, roughly corresponding to the Intuitive idea of how much Matter there is in an object It is concentrated in stars, where it is formed from hydrogen by the nuclear fusion of the proton-proton chain reaction and CNO cycle. Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 In Physics and Nuclear chemistry, nuclear fusion is the process by which multiple- like charged atomic nuclei join together to form a heavier nucleus The proton-proton chain reaction is one of several fusion reactions by which Stars convert Hydrogen to Helium, the primary alternative being the The CNO cycle (for Carbon - Nitrogen - Oxygen) or sometimes Bethe-Weizsäcker-cycle, is one of two sets of fusion reactions 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. The Big Bang is the cosmological model of the Universe that is best supported by all lines of scientific evidence and Observation. In Physical cosmology, Big Bang nucleosynthesis (or primordial nucleosynthesis) refers to the production of nuclei other than those of H-1 (i As such, measurements of its abundance contribute to cosmological models.

In the Earth's atmosphere, the concentration of helium by volume is only 5. Temperature and layers The temperature of the Earth's atmosphere varies with altitude the mathematical relationship between temperature and altitude varies among five 2 parts per million. [29] 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. There are several different processes that can lead to the escape of a planetary atmosphere. [30][31] In the Earth's heterosphere, a part of the upper atmosphere, helium and other lighter gases are the most abundant elements. Temperature and layers The temperature of the Earth's atmosphere varies with altitude the mathematical relationship between temperature and altitude varies among five

Nearly all helium on Earth is a result of radioactive decay. Radioactive decay is the process in which an unstable Atomic nucleus loses energy by emitting ionizing particles and Radiation. The decay product is primarily found in minerals of uranium and thorium, including cleveites, pitchblende, carnotite and monazite, because they emit alpha particles, which consist of helium nuclei (He2+) to which electrons readily combine. In Nuclear physics, a decay product, also known as a daughter product, daughter isotope or daughter nuclide, is a Nuclide Uranium (jʊˈreɪniəm is a silvery-gray Metallic Chemical element in the Thorium (ˈθɔːriəm is a Chemical element with the symbol Th and Atomic number 90 Cleveite is a radioactive Mineral containing Uranium and found in Norway. Carnotite is a Potassium Uranium Vanadate Mineral with Chemical formula: K 2( U[[oxygen O]]22( In Geology, the Mineral monazite is a reddish-brown Phosphate -containing rare earth metals and an important source of Thorium Alpha particles (named after and denoted by the first letter in the Greek alphabet, α consist of two Protons and two Neutrons bound together into a 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. A spring is a point where Groundwater flows out of the ground and is thus where the Aquifer surface meets the ground surface Plate tectonics and hotspots Divergent plate boundaries At the The greatest concentrations on the planet are in natural gas, from which most commercial helium is derived. Natural gas is a Gaseous Fossil fuel consisting primarily of Methane but including significant quantities of Ethane, Propane,

Modern extraction

For large-scale use, helium is extracted by fractional distillation from natural gas, which contains up to 7% helium. 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 Natural gas is a Gaseous Fossil fuel consisting primarily of Methane but including significant quantities of Ethane, Propane, [32] 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). Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 Methane is a Chemical compound with the molecular formula. It is the simplest Alkane, and the principal component of Natural gas. 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. Activated carbon, also called activated charcoal or activated coal, is a form of Carbon that has been processed to make it extremely porous and thus to 995% pure, Grade-A, helium. [33] The principal impurity in Grade-A helium is neon. Neon (ˈniːɒn is the Chemical element that has the symbol Ne and Atomic number 10 In a final production step, most of the helium that is produced is liquefied via a cryogenic process. Cryogenics is often used incorrectly to refer to Cryonics, cryopreserving humans or animals 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. A semipermeable membrane, also termed a selectively-permeable membrane, a partially-permeable membrane or a differentially-permeable membrane, is a membrane Helium can be synthesized by bombardment of lithium or boron with high-velocity protons, but this is not an economically viable method of production. Lithium (ˈlɪθiəm is a Chemical element with the symbol Li and Atomic number 3 Boron (ˈbɔərɒn is a Chemical element with Atomic number 5 and the chemical symbol B. The proton ( Greek πρῶτον / proton "first" is a Subatomic particle with an Electric charge of one positive

Isotopes

Main article: Isotopes of helium

There are eight known isotopes of helium, but only helium-3 and helium-4 are stable. Although there are eight known Isotopes of Helium ( He) (standard atomic mass 4 Isotopes (Greek isos = "equal" tópos = "site place" are any of the different types of atoms ( Nuclides This article is about the elemental isotope For the record label Helium 3 see Muse or A&E Records. Helium-4 ( or) is a non- Radioactive and light Isotope of Helium. Stable isotopes are chemical isotopes that are not Radioactive (to current knowledge In the Earth's atmosphere, there is one He-3 atom for every million He-4 atoms. [34] Unlike most elements, helium's isotopic abundance varies greatly by origin, due to the different formation processes.

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. Alpha decay is a type of radioactive decay in which an Atomic nucleus emits an Alpha particle (two protons and two neutrons bound together into a particle Alpha particles (named after and denoted by the first letter in the Greek alphabet, α consist of two Protons and two Neutrons bound together into a Helium-4 is an unusually stable nucleus because its nucleons are arranged into complete shells. 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 which uses the Pauli principle to describe the structure It was also formed in enormous quantities during Big Bang nucleosynthesis. In Physical cosmology, Big Bang nucleosynthesis (or primordial nucleosynthesis) refers to the production of nuclei other than those of H-1 (i

Helium-3 is present on Earth only in trace amounts; most of it since Earth's formation, though some falls to Earth trapped in cosmic dust. [35] Trace amounts are also produced by the beta decay of tritium. In Nuclear physics, beta decay is a type of Radioactive decay in which a Beta particle (an Electron or a Positron) is emitted Tritium (ˈtɹɪtiəm symbol or, also known as Hydrogen-3) is a radioactive Isotope of Hydrogen. [36] Rocks from the Earth's crust have isotope ratios varying by as much as a factor of ten, and these ratios can be used to investigate the origin of rocks and the composition of the Earth's mantle. The mantle is a part of an Astronomical object. The interior of the Earth, similar to the other Terrestrial planets, is Chemically divided [35] He-3 is much more abundant in stars, as a product of nuclear fusion. A star is a massive luminous ball of plasma. The nearest star to Earth is the Sun, which is the source of most of the Energy on Earth In Physics and Nuclear chemistry, nuclear fusion is the process by which multiple- like charged atomic nuclei join together to form a heavier nucleus Thus in the interstellar medium, the proportion of He-3 is around 100 times higher than on Earth. [37] Extraplanetary material, such as lunar and asteroid regolith, have trace amounts of helium-3 from being bombarded by solar winds. Asteroids, sometimes called Minor planets or planetoids', are bodies—primarily of the inner Solar System —that are smaller than planets but Regolith ( Greek: "blanket rock" is a layer of loose Heterogeneous material covering solid rock. The solar wind is a Stream of charged particles&mdasha plasma &mdashthat are ejected from the upper atmosphere of the Sun. The Moon's surface contains helium-3 at concentrations on the order of 0. 01 ppm. "Parts-per" notation is used especially in Science and Engineering, to denote Ratios (relative proportions in measured quantities particularly [38][39] A number of people, starting with Gerald Kulcinski in 1986,[40] have proposed to explore the moon, mine lunar regolith and use the helium-3 for fusion. The physical exploration of the Moon began when Luna 2, a Space probe launched by the Soviet Union, impacted the surface of the Moon on In Physics and Nuclear chemistry, nuclear fusion is the process by which multiple- like charged atomic nuclei join together to form a heavier nucleus

Liquid helium-4 can be cooled to about 1 kelvin using evaporative cooling in a 1-K pot. The kelvin (symbol K) is a unit increment of Temperature and is one of the seven SI base units The Kelvin scale is a thermodynamic Evaporative coolers (also called swamp, desert, or air coolers) are devices that cool air through the simple Evaporation of water Similar cooling of helium-3, which has a lower boiling point, can achieve about 0. 2 kelvin in a helium-3 refrigerator. A helium-3 refrigerator is a simple device used in experimental Physics for obtaining Temperatures down to about 0 Equal mixtures of liquid He-3 and He-4 below 0. 8 K 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). Particle statistics refers to the particular description of particles in Statistical mechanics. In Particle physics, bosons are particles which obey Bose-Einstein statistics; they are named after Satyendra Nath Bose and Albert Einstein In Particle physics, fermions are particles which obey Fermi-Dirac statistics; they are named after Enrico Fermi. [41] Dilution refrigerators use this immiscibility to achieve temperatures of a few millikelvins. A dilution refrigerator is a cryogenic device first proposed by Heinz London.

It is possible to produce exotic helium isotopes, which rapidly decay into other substances. Although there are eight known Isotopes of Helium ( He) (standard atomic mass 4 The shortest-lived heavy helium isotope is helium-5 with a half-life of 7. Half-Life (computer-game page here It's already listed in the disambiguation page 6×10−22 seconds. Helium-6 decays by emitting a beta particle and has a half life of 0. Beta particles are high-energy high-speed Electrons or Positrons emitted by certain types of Radioactive nuclei such as Potassium -40 8 seconds. Helium-7 also emits a beta particle as well as a gamma ray. Gamma rays (denoted as &gamma) are a form of Electromagnetic radiation or light emission of frequencies produced by sub-atomic particle interactions Helium-7 and helium-8 are hyperfragments that are created in certain nuclear reactions. In Nuclear physics, a nuclear reaction is the process in which two nuclei or nuclear particles collide to produce products different from the initial particles [42] Helium-6 and helium-8 are known to exhibit a nuclear halo. In Nuclear physics, an atomic nucleus is called a halo nucleus or is said to have a nuclear halo if its radius is appreciably larger than that predicted by the Helium-2 (two protons, no neutrons) is a radioisotope that decays by proton emission into protium (hydrogen), with a half-life of 3x10−27 second. A radionuclide is an Atom with an unstable nucleus, which is a nucleus characterized by excess energy which is available to be imparted either to a newly-created Proton emission (also known as proton radioactivity is a type of radioactive decay in which a Proton is ejected from a nucleus. A hydrogen atom is an atom of the chemical element Hydrogen. The electrically neutral Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Half-Life (computer-game page here It's already listed in the disambiguation page [41]

Biological effects

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 the speed of sound in air. Sound is a vibration that travels through an elastic medium as a Wave. 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. The fundamental tone, often referred to simply as the fundamental and abbreviated fo, is the lowest frequency in a harmonic series. In Physics, resonance is the tendency of a system to Oscillate at maximum Amplitude at certain frequencies, known as the system's 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 [21] (The opposite effect, lowering frequencies, can be obtained by inhaling sulfur hexafluoride)

Inhaling helium can be dangerous if done to excess, since helium is a simple asphyxiant and so displaces oxygen needed for normal respiration. Sulfur hexafluoride is an Inorganic compound with the formula. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the In Animal physiology, respiration is the transport of Oxygen from the outside air to the cells within tissues and the transport of Carbon dioxide Breathing pure helium continuously causes death by asphyxiation within minutes. In most mammals (except seals and many burrowing animals) 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. Mammals ( class Mammalia) are a class of Vertebrate Animals characterized by the presence of Sweat glands, including sweat glands Pinnipeds ("fin-feet" lit "winged feet" or fin-footed mammals are a widely distributed and diverse group of semi-aquatic marine Mammals comprising A reflex action, also known as a reflex, is an involuntary and almost instant movement in response to stimulus. Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single Air hunger is the Sensation of the urge to Breathe It is usually caused by the detection of high levels of Carbon dioxide in the blood by sensors in the Inhaling helium directly from pressurized cylinders is extremely dangerous, as the high flow rate can result in barotrauma, fatally rupturing lung tissue. 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 lung is the essential Respiration organ in air-breathing Animals including most Tetrapods a few Fish and a few Snails The most primitive [43]

Neutral helium at standard conditions is non-toxic, plays no biological role and is found in trace amounts in human blood. At high pressures (more than about 20 atm or two MPa), a mixture of helium and oxygen (heliox) can lead to high pressure nervous syndrome, a sort of reverse-anesthetic effect; adding a small amount of nitrogen to the mixture can alleviate the problem. See Heliox (cryogenic equipment for another use of the word Heliox Heliox is a Breathing gas composed of a mixture of High pressure nervous syndrome ( HPNS) is a Neurological and Physiological diving disorder that results when a diver spends too much [44]

Containers of helium gas at 5 to 10 K should be handled as if they contain liquid helium due to the rapid and significant thermal expansion that occurs when helium gas at less than 10 K is warmed to room temperature. Thermal Expansion is the tendency of matter to change in Volume in response to a change in temperature Room temperature (also referred to as ambient temperature) is a common term to denote a certain Temperature within enclosed space at which humans are accustomed [3]

Compounds

See also: Noble gas compound

Helium is chemically unreactive under all normal conditions due to its valence of zero. Noble gas compounds are Chemical compounds that include an element from Group 18 Noble gas In Chemistry, valence, also known as valency or valency number, is a measure of the number of Chemical bonds formed by the Atoms [45] It is an electrical insulator unless ionized. An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge 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. A quantum mechanical system or particle that is bound, confined spacially can only take on certain discrete values of energy as opposed to classical particles which Electrical tension (or voltage after its SI unit, the Volt) is the difference of electrical potential between two points of an electrical The ionization potential, ionization energy or EI of an Atom or Molecule is the Energy required to remove an Electron 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. A chemical compound is a substance consisting of two or more different elements chemically bonded together in a fixed proportion by Mass. Tungsten (ˈtʌŋstən also known as wolfram (/ˈwʊlfrəm/ is a Chemical element that has the symbol W and Atomic number 74 Iodine (ˈaɪədaɪn ˈaɪədɪn or /ˈaɪədiːn/ from ιώδης iodes "violet" is a Chemical element that has the symbol I and Atomic Fluorine, fluorum meaning "to flow" is the Chemical element with the symbol F and Atomic number 9 Sulfur or sulphur (ˈsʌlfɚ see spelling below) is the Chemical element that has the Atomic number 16 Phosphorus, (ˈfɒsfərəs is the Chemical element that has the symbol P and Atomic number 15 Electric glow discharge is a type of plasma formed by passing a current at 100 V to several kV through a gas usually Argon or another Noble In Physics and Chemistry, plasma is an Ionized Gas, in which a certain proportion of Electrons are free rather than being bound HeNe, HgHe10, WHe2 and the molecular ions He2+, He22+, 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. Spectral bands are part of optical spectra of polyatomic systems including condensed materials large molecules etc [1] Theoretically, other compounds may also be possible, such as helium fluorohydride (HHeF) which would be analogous to HArF, discovered in 2000. Argon fluorohydride (HArF is the first known compound of the Chemical element Argon.

Helium has been put inside the hollow carbon cage molecules (the fullerenes) by heating under high pressure of the gas. "C60" and "C-60" redirect here For other uses see C60 (disambiguation. 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. This article is about the elemental isotope For the record label Helium 3 see Muse or A&E Records. Many fullerenes containing helium-3 have been reported. Although the helium atoms are not attached by covalent or ionic bonds, 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
Table

Notes

  1. ^ a b The Encyclopedia of the Chemical Elements, edited by Cifford A. Events 680 - Battle of Karbala: Shia Imam Husayn bin Ali, the grandson of the Prophet Muhammad, is decapitated See also 2002 (disambiguation Year 2002 ( MMII) was a Common year starting on Tuesday of the Gregorian calendar. Hampel, "Helium" entry by L. W. Brandt (New York; Reinhold Book Corporation; 1968; page 261) Library of Congress Catalog Card Number: 68-29938
  2. ^ Helium (He) and water
  3. ^ a b c Los Alamos National Laboratory (LANL. gov): Periodic Table, "Helium" (viewed 10 October 2002 and 25 March 2005)
  4. ^ C. Events 680 - Battle of Karbala: Shia Imam Husayn bin Ali, the grandson of the Prophet Muhammad, is decapitated See also 2002 (disambiguation Year 2002 ( MMII) was a Common year starting on Tuesday of the Gregorian calendar. Events 1199 - Richard I is wounded by a crossbow bolt while fighting France which leads to his death on April 6. Year 2005 ( MMV) was a Common year starting on Saturday (link displays full calendar of the Gregorian calendar. Malinowska-Adamska, P. Soma, J. Tomaszewski (2003). "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. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.  
  5. ^ Solid Helium, Dept. of Physics, at the University of Alberta
  6. ^ Structure of Solid Helium by Neutron Diffraction, D. G. Henshaw, Physical Review Letters 109, Pg.  328 – 330 (Issue 2 – January 1958)
  7. ^ a b c The Encyclopedia of the Chemical Elements, page 262
  8. ^ Yuan, Sidney. The Two Fluid Model of Superfluid Helium (He II, Superfluidity). Yutiopian. com. Retrieved on 5 January 2007.
  9. ^ a b The Encyclopedia of the Chemical Elements, page 263
  10. ^ Fairbank H. A. ; Lane C. T. (October 1949). "Rollin Film Rates in Liquid Helium". Physical Review 76 (8): 1209–1211. doi:10.1103/PhysRev.76.1209. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.  
  11. ^ Ellis, Fred M. Third sounds. Wesleyan Quantum Fluids Laboratory. Retrieved on 2007-11-08. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1519 - Hernán Cortés enters Tenochtitlán and Aztec ruler Moctezuma welcomes him with great a Celebration
  12. ^ Warner, Brent. Introduction to Liquid Helium. NASA. Archived from the original on 2005-09-01. Year 2005 ( MMV) was a Common year starting on Saturday (link displays full calendar of the Gregorian calendar. Events 462 - Possible start of first Byzantine indiction cycle. Retrieved on 2007-01-05. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1477 - Battle of Nancy: Charles the Bold is killed and Burgundy becomes part of France.
  13. ^ LHC Guide booklet CERN - LHC: Facts and Figures. CERN. The European Organization for Nuclear Research (Organisation Européenne pour la Recherche Nucléaire known as CERN Retrieved on 2008-04-30. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Events 313 - Roman emperor Licinius unifies the entire Eastern Roman Empire under his rule
  14. ^ Physics in speech, phys. unsw. edu. au. Retrieved on 5 January 2007. Events 1477 - Battle of Nancy: Charles the Bold is killed and Burgundy becomes part of France. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century.
  15. ^ The Encyclopedia of the Chemical Elements, page 256
  16. ^ 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. "
  17. ^ a b c The Encyclopedia of the Chemical Elements, page 257
  18. ^ William Ramsay (1895). Sir William Ramsay (2 October 1852 &ndash 23 July 1916 was a Scottish chemist who discovered the Noble gases and received the Nobel Prize in "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. doi:10.1098/rspl.1895.0006. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.  
  19. ^ William Ramsay (1895). Sir William Ramsay (2 October 1852 &ndash 23 July 1916 was a Scottish chemist who discovered the Noble gases and received the Nobel Prize in "Helium, a Gaseous Constituent of Certain Minerals. Part I". Proceedings of the Royal Society of London 58: 80–89. doi:10.1098/rspl.1895.0010. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.  
  20. ^ William Ramsay (1895). Sir William Ramsay (2 October 1852 &ndash 23 July 1916 was a Scottish chemist who discovered the Noble gases and received the Nobel Prize in "Helium, a Gaseous Constituent of Certain Minerals. Part II--". Proceedings of the Royal Society of London 59: 325–330. doi:10.1098/rspl.1895.0097. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.  
  21. ^ a b Emsley, Nature's Building Blocks, 177
  22. ^ Pat Munday (1999). Pat Munday is an environmentalist writer and college professor living in Butte Montana 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.
  23. ^ a b Emsley, Nature's Building Blocks, 179
  24. ^ American Chemical Society (2004). The American Chemical Society ( ACS) is a Learned society ( Professional association) based in the United States that supports scientific inquiry The Discovery of Helium in Natural Gas. Retrieved on 2006-05-17. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Events 1521 - Edward Stafford 3rd Duke of Buckingham, is executed for Treason.
  25. ^ (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. The National Aeronautics and Space Administration ( NASA, ˈnæsə is an agency of the United States government, responsible for the nation's public space program Retrieved on 2007-01-05. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1477 - Battle of Nancy: Charles the Bold is killed and Burgundy becomes part of France.  
  26. ^ Guide to the Elements: Revised Edition, by Albert Stwertka (New York; Oxford University Press; 1998; page 24) ISBN 0-19-512708-0
  27. ^ Helium Privatization Act of 1996. Retrieved on 2007-01-05. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1477 - Battle of Nancy: Charles the Bold is killed and Burgundy becomes part of France.
  28. ^ Executive Summary, nap. edu. Retrieved on 5 January 2007. Events 1477 - Battle of Nancy: Charles the Bold is killed and Burgundy becomes part of France. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century.
  29. ^ The Atmosphere: Introduction. JetStream - Online School for Weather. National Weather Service. The National Weather Service ( NWS) once known as the Weather Bureau is one of the six scientific agencies that make up the National Oceanic and Atmospheric Administration
  30. ^ 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. Journal of Geophysical Research is the premier journal of the American Geophysical Union. doi:10.1029/95JA02208. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.  
  31. ^ Strobel, Nick (2007). Nick Strobel's Astronomy Notes. Retrieved on 2007-09-25. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 303 - On a voyage preaching the Gospel, Saint Fermin of Pamplona is beheaded in Amiens, France
  32. ^ WebElements Periodic Table: Professional Edition: Helium: key information
  33. ^ The Encyclopedia of the Chemical Elements, page 258
  34. ^ 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
  35. ^ a b Helium Fundamentals
  36. ^ Periodic Table of Elements: Li - Lithium (EnvironmentalChemistry.com)
  37. ^ Zastenker G. N. ; Salerno E. ; Buehler F. ; Bochsler P. ; Bassi M. ; Agafonov Y. N. ; Eismont N. A. ; Khrapchenkov V. V. ; Busemann H. (April 2002). "Isotopic Composition and Abundance of Interstellar Neutral Helium Based on Direct Measurements". Astrophysics 45 (2): 131–142. doi:10.1023/A:1016057812964. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.  
  38. ^ FTI Research Projects :: 3He Lunar Mining
  39. ^ E. N. Slyuta and A. M. Abdrakhimov, and E. M. Galimov (2007). The estimation of helium-3 probable reserves in lunar regolith. Lunar and Planetary Science XXXVIII.
  40. ^ Eric R. Hedman. "A fascinating hour with Gerald Kulcinski", The Space Review, January 16, 2006.  
  41. ^ a b The Encyclopedia of the Chemical Elements, page 264
  42. ^ The Encyclopedia of the Chemical Elements, page 260
  43. ^ Stay Out of That Balloon! The dangers of helium inhalation, Slate. com. Retrieved on 18 September 2007. Events 96 - Nerva is proclaimed Roman Emperor after Domitian is assassinated Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century.
  44. ^ HPNS, scuba-doc. com. Retrieved on 5 January 2007. Events 1477 - Battle of Nancy: Charles the Bold is killed and Burgundy becomes part of France. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century.
  45. ^ Helium - Valency. Retrieved on 14 May 2008. Events 1264 - Battle of Lewes: Henry III of England is captured in France making Simon de Montfort the 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common

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Dictionary

helium

-noun

  1. (uncountable) A colorless and inert gas, and the second lightest chemical element (symbol He) with an atomic number of 2 and atomic weight of 4.002602.
  2. (countable) A form or sample of the element.
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