Helium

HCID 23987

Basic information

CAS
71086-78-7
Standard SMILES
[He]
InChIKey
SWQJXJOGLNCZEY-UHFFFAOYSA-N
Molecular formula
He
Average molar mass
4.0026 g/mol
Monoisotopic mass
4.00260325

Overview

Helium appears as a colorless, odorless, noncombustible gas. Can asphyxiate. Inhalation causes the voice to become squeaky (Mickey Mouse voice). Exposure of the container to prolonged heat or fire can cause it to rupture violently and rocket. If liquefied, contact of the very cold liquid with water causes violent boiling. Pressures may build to dangerous levels if the liquid contacts water in a closed container. Used in arc welding, to trace leaks in refrigeration and other closed systems and as a lifting gas for lighter-than-air aircraft.

Names & identifiers

Preferred name
Helium
IUPAC
helium
English name
HELIUM
Molecular formula
He
Molecular weight
4

Names & synonyms

HELIUMAtomic heliumHelium-47440-59-7p-HeliumO-HeliumHelium (USP)Helium 4Helium [USP]INS NO.939E939INS-939
Show more names
Hehelium, liquidHelium(0)heliumgasHELIUMIONSHelium(4He)
206GF3GB41E-939DTXSID7036402CHEBI:30217CHEBI:3368171086-78-7CHEBI:30218CHEBI:30219

Database identifiers

CAS
71086-78-7、7440-59-7
PubChem CID
23987
DTXSID
DTXSID7036402
ChEMBL
CHEMBL1796997
ChEBI
CHEBI:33681
UNII
206GF3GB41
EC Number
231-168-5、275-187-7
Nikkaji
J3.101A

Properties

Computed structural properties

Topological polar surface area
0 Ų
Hydrogen bond donors
0
Hydrogen bond acceptors
0
Rotatable bonds
0
Heavy atoms
1

Experimental & physicochemical properties

Chemical ClassesToxic Gases & Vapors -> Simple Asphyxiants
SpringerMaterials Propertieselectron-phonon coupling
LogP0.28
OdorOdorless
TasteTasteless
Food AdditivesPROCESSING AID -> FDA Substance added to food

Physicochemical properties

Melting point
-272.2 °C · -272.2 °C(lit.)
Boiling point
-268.934 °C · -268.934 °C(lit.)
Density
0.1785 · 0.1785(0℃)
vapor density
0.14 · 0.14 (vs air)
solubility
2 O; · slightly soluble in H2O; insoluble in ethanol
form
gas

Safety & regulation

GHS classification

GHS Classification · 6 items

This chemical does not meet GHS hazard criteria for 0.4% (2 of 491) of reports.

Warning

H280 (65.6%): Contains gas under pressure; may explode if heated [Warning Gases under pressure]

P282, P336+P317, P403, and P410+P403 (click each P-code to see the statement)

Aggregated GHS information provided per 491 reports by companies from 6 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.

Warning

Hazard information

Regulatory Information · 4 items

Chemical: Helium

Helium is listed on the EPA's Chemical Data Reporting (CDR) system. Manufacturers and importers of Helium are required to report information about their production and use of this chemical to the EPA under the Toxic Substances Control Act (TSCA). (40 eCFR Part 711)

Helium: Non hazardous

The New Jersey Worker and Community Right to Know Act requires public and private employers to provide information about hazardous substances at their workplaces. (N.J.S.A. 34:5A-1 et. seq.)

Other Safety InformationIMAP assessments - Helium: Human health tier I assessment
DOT Label · 2 items

Non-Flammable Gas

Non-Flammable Gas

Fire Hazards · 5 items

Excerpt from ERG Guide 120 [Gases - Inert (Including Refrigerated Liquids)]:

Excerpt from ERG Guide 120 [Gases - Inert (Including Refrigerated Liquids)]:

· Non-flammable gases.

· Non-flammable gases.

Not combustible. Heating will cause rise in pressure with risk of bursting.

Fire PotentialNot combustible. Heating will cause rise in pressure with risk of bursting.
Health Hazards · 4 items

Excerpt from ERG Guide 120 [Gases - Inert (Including Refrigerated Liquids)]:

Excerpt from ERG Guide 120 [Gases - Inert (Including Refrigerated Liquids)]:

· Vapors may cause dizziness or asphyxiation without warning, especially when in closed or confined areas.

· Vapors may cause dizziness or asphyxiation without warning, especially when in closed or confined areas.

Safety & protection

Fire Fighting · 3 items

Excerpt from ERG Guide 120 [Gases - Inert (Including Refrigerated Liquids)]:

Excerpt from ERG Guide 120 [Gases - Inert (Including Refrigerated Liquids)]:

In case of fire in the surroundings, use appropriate extinguishing media. In case of fire: keep cylinder cool by spraying with water.

First Aid Measures · 3 items

Fresh air, rest. Artificial respiration may be needed. Refer for medical attention.

ON FROSTBITE: rinse with plenty of water, do NOT remove clothes. Refer for medical attention .

First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then refer for medical attention.

Accidental Release Measures · 4 items

· CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper not available or no answer, refer to appropriate telephone number listed on the inside back cover.

· Do not touch or walk through spilled material.

· CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper not available or no answer, refer to appropriate telephone number listed on the inside back cover.

· Do not touch or walk through spilled material.

First Aid · 4 items

Excerpt from ERG Guide 120 [Gases - Inert (Including Refrigerated Liquids)]:

Excerpt from ERG Guide 120 [Gases - Inert (Including Refrigerated Liquids)]:

General First Aid:

General First Aid:

Safe StorageFireproof if in building. Keep in a well-ventilated room.
Exposure Control and Personal Protection · 2 items

· Wear positive pressure self-contained breathing apparatus (SCBA).

· Wear positive pressure self-contained breathing apparatus (SCBA).

Toxicology

Adverse EffectsOther Poison - Simple Asphyxiant
Exposure RoutesThe substance can be absorbed into the body by inhalation.
Signs and Symptoms · 3 items

Dizziness. Lethargy. Headache. Suffocation.

ON CONTACT WITH LIQUID: FROSTBITE.

ON CONTACT WITH LIQUID: FROSTBITE.

Natural Pollution Sources · 5 items

Helium is a product of the nuclear fusion reactions that are the prime source of stellar energy; it is plentiful in the cosmos. The principal source of helium is certain natural gas fields(1). Except for hydrogen, helium is the most abundant element found throughout the universe(2).

Texas, Oklahoma, Kansas, New Mexico, Arizona, Canada. Originally discovered in the sun's atmosphere (1868) and confirmed in the atmosphere of Jupiter.

Abundance in igneous rock of earth's crust: 3X10-3 ppm by weight; concentration in air: 5.24 ppm by volume. Identified in the spectrum of the sun's chromosphere ... Found in natural gas from which it is extracted on a commercial scale. Produced by the decay of radioactive elements: 1 kg uranium in its conversion into 865 g of lead forms 756 L of helium; also produced in nature by the bombardment of berylium, lithium, and other light elements with cosmic rays, x-rays, and high-speed protons and deuterons.

Helium is present at a level of only about 2 nano-moles per kg of seawater. Sources include helium dissolved from the atmosphere and helium that is released from volcanic or hydrothermal activity near the ocean floor(1).

The helium content of the atmosphere is about 1 part in 200,000(1). The content of He-3 and He-4 in the atmosphere is 6.8X10-10 mol% and 5.24X10-5 mol%, respectively. The content of He-4 in atmospheric noble gas is 0.56 mol%(2). The concentration of He-4 in dry air is reported as 5.24 uL/L(3).

Atmospheric Concentrations · 1 item

The helium content of the atmosphere is about 1 part in 200,000(1). The content of He-3 and He-4 in the atmosphere is 6.8X10-10 mol% and 5.24X10-5 mol%, respectively. The content of He-4 in atmospheric noble gas is 0.56 mol%(2). The concentration of He-4 in dry air is reported as 5.24 uL/L(3).

Human Toxicity Excerpts · 5 items

/HUMAN EXPOSURE STUDIES/ The aim of the present study was to examine the effects of simulated heliox diving at high altitudes on divers' blood cells, liver functions and renal functions. In this experiment, four divers lived for nine consecutive days in a dual-function high-low pressure chamber, which simulated air pressure at an altitude of 3,000 meters and at a 30-meter depth; an altitude of 4,000 meters and 30-meter depth; and at an altitude of 5,200 meters and 30 meters and 50 meters in depth. Total time underwater was 60 minutes. The subjects breathed heliox (with oxygen at 40% and helium at 60%) during the simulated 30-meter dive from zero altitude to 30 meters and while remaining underwater; they breathed air while ascending from 30 meters to 18. They breathed heliox (with oxygen at 26.7% and helium at 73.3%) in the simulated dive from zero altitude to 50 meters underwater, in remaining underwater and in ascending from 50 meters to 29; air while ascending from 29 meters to 18. Pure oxygen was breathed while ascending from 18 meters to the surface; then air. Results indicated: (1) the correlating indices of routine blood, liver and renal functions, and urine routine were all within normal reference ranges; and (2) the indices tested at other periods of time were not significantly different (p > 0.05) from the results at zero-meter level and 3,000-meter level. The study suggests that the heliox diving processes at different high altitudes simulated in this experiment have no significant impact upon divers' blood routine, liver functions and renal functions.

/SIGNS AND SYMPTOMS/ Although helium-related fatalities and concerns about potentially harmful effects of helium use have increased in recent years, virtually nothing is known about the epidemiology of helium inhalation in adolescents. This exploratory investigation examined the prevalence and correlates of helium inhalation in a large sample of at-risk youth. Study participants were 723 Missouri adolescents (M age = 15.5, SD = 1.2) in residential treatment for delinquent behavior. More than one-in-nine (N = 81, 11.5%) adolescents had inhaled helium with the intention of getting high, and one-third (N = 27, 34.2%) of helium users reported they actually did get high when they inhaled helium. Helium users were significantly more likely to be Caucasian, to live in rural/small town areas, and to have histories of mental illness, auditory hallucinations, and alcohol and marijuana use than nonusers. Helium users also reported significantly more current psychiatric distress, suicidality, traumatic life experiences, and antisocial attitudes, traits, and behaviors than nonusers. Helium inhalation was prevalent in this sample and many such users reported getting high while using helium. Helium users had psychosocial profiles similar to those of volatile solvent users, suggesting that they may be at substantial risk for a variety of adverse health outcomes.

/CASE REPORTS/ A 23-year-old man was found on a raised hide in lying position, the head wrapped in a plastic bag connected with a helium gas cylinder by a polypropylene tube. The autopsy did not show any specific findings nor did the routine toxicological analysis reveal significant information regarding the cause of death (BAC 0.9 mg/g, diphenhydramine 0.81 ug/mL in heart serum). For the detection of helium in the lungs, gas samples from both lungs were collected by a method ensuring minimal dilution. Gas analyses were performed using a GC-MS with a split-splitless injector and a headspace syringe. As carrier gas the commonly used helium was replaced by nitrogen. Helium was found in clearly elevated concentrations in gas samples from both lungs. Therefore, suffocation by breathing helium enriched, and thus oxygen deficient atmosphere, can strongly be assumed as the cause of death.

/CASE REPORTS/ Suicide by asphyxiation using helium is the most widely-promoted method of "self-deliverance" by right-to-die advocates. However, little is known about persons committing such suicides or the circumstances and manner in which they are completed. Prior reports of suicides by asphyxiation involving helium were reviewed and deaths determined by the North Carolina Office of the Chief Medical Examiner to be helium-associated asphyxial suicides occurring between January 1, 2000 and December 31, 2008 were included in a new case series examined in this article. The 10 asphyxial suicides involving helium identified in North Carolina tended to occur almost exclusively in non-Hispanic, white men who were relatively young (M age = 41.1 T 11.6). In 6 of 10 cases, decedents suffered from significant psychiatric dysfunction; in 3 of these 6 cases, psychiatric disorders were present comorbidly with substance abuse. In none of these cases were decedents suffering from terminal illness. Most persons committing suicide with helium were free of terminal illness but suffered from psychiatric and/or substance use disorders.

For more Human Toxicity Excerpts (Complete) data for HELIUM (7 total), please visit the HSDB record page.

Regulatory information

FDA RequirementsSubstance added directly to human food affirmed as generally recognized as safe (GRAS).

Safety data

F
4.5-31
wgk
3
tsca
TSCA listed
rtecs
MH6520000
ridadr
UN 1963 2.2 (HELIUM, REFRIGERATED LIQUID)
Signal word
Warning

Chemistry & industry

Pharmacology

ATC Code · 2 items

V - Various

QV - Various

Pharmacodynamics · 1 item

Helium provides lung ventilation and prevents narrowing or collapse in respiratory units. It increases the tendency to laminar flow and reduces the resistance in turbulent flow, leading to more efficient penetration of gases to the distal alveoli, higher minute volumes and improved ventilation.

Mechanism of Action · 1 item

Due to its lower density, helium achieves more effective flow of gas due to lowered resistance to gas flow within the airways and reduces the work of breathing by decreasing the pressure gradient needed to achieve a turbulent flow. Helium has a higher diffusion coefficient for carbon dioxide relative to oxygen thus promotes exhalation of trapped carbon dioxide. This reduces hypercapnia and normalizes pH. Helium increases the coronary collateral circulation and enhances the vasodilatory effects of inhaled nitric oxide on pulmonary vessels. It is suggested to possess neuroprotective properties. Cardioprotective effects against ischemia are mediated through early and late preconditioning by exposing the myocardial tissues to short ischemic episodes. Studies show that helium is associated with activation of pro-survival signalling kinases and inhibition of the opening of mitochondrial permeability transition pore (mPTP).

Biological Half-Life0.8 seconds
Absorption, Distribution and Excretion · 2 items

Respiration

Helium ... is quite insolubility in body tissues.

Cellular LocationsCytoplasm

Uses & manufacturing

Uses · 6 items

Used as an inert gas in arc welding; Also used in balloons, airships, lamps, electronic tubes, and cryogenic applications; [ACGIH] Also used to replace nitrogen in breathing supply of high-pressure divers and as a coolant for nuclear reactors; [Merck Index # 4630] Also used for leak detection, growing crystals (germanium and silicon), transferring heat, and producing lasers; [Hawley]

Welding [Category: Weld]

Liquid helium (the most volatile liquid known) as cryogen for the production of low temps, in MRI machines. Gas in manufacture of semiconducting devices; in detection devices for leaks in vacuum systems; in Ne-He lasers; in gas mixtures as the working fluid in plasma devices; in mixtures with Ne and Ar in Geiger counters. Q-Gas, a mixture of 98.7% He and 1.3% butane, has been used as a filing for gas-flow Geiger counters. Gas as a shield in gas tungsten-arc welding, in metal processing; substitute for N2 in synthetic breathing gas for deep sea divers and workers in high pressure conditions; coolant in high temperature nuclear reactors; carrier gas in gas-liquid and gas-solid chromatography; inert diluent; to create inert atmosphere; to fill balloons and airships

Cooling medium for nuclear reactors; gas for supersonic wind tunnels

Inert atmosphere (growing germanium and silicon crystals); magnetohydrodynamics; luminous signs; geological dating

Helium is essential to many high-technology processes ... the production of optical glass fibers, in which it serves as a coolant and as a carrier gas for the chlorine used for the removal of hydroxyl groups.

ImpuritiesImpurities /potential/: water, total hydrocarbons as methane; oxygen; nitrogen; neon; hydrogen; and CO/CO2
U.S. Exports · 5 items

(1972) 6.48X10+8 GRAMS

(1975) 8.2X10+8 GRAMS

(1985) 1.27X10+7 cu m /Grade A Helium/

(1988) 18.4X10+6 cu m

For more U.S. Exports (Complete) data for HELIUM (9 total), please visit the HSDB record page.

U.S. Imports · 2 items

(1985) No imports - US is a net exporter

(1986-1989) None

U.S. Production · 6 items

2023: 1,000,000 - <8,500,000 lb

(1972) 1.63X10+10 GRAMS

(1975) 4.69X10+9 GRAMS

(1988) Domestic sales: 53.0X10+6 cu m; Total sales: 71.4X10+6 cu m

(1989) Domestic sales: 57.8X10+6 cu m; Total sales: 79.9X10+6 cu m

For more U.S. Production (Complete) data for HELIUM (12 total), please visit the HSDB record page.

Consumption Patterns · 5 items

About 20% in welding; about 17% in purging & pressurizing rockets & spacecraft; about 17% as a research chem; about 8% as a heat transfer agent; about 6% in leak detection; about 6% as a component of synthetic breathing mixtures; about 5% in cryogenic applications; about 4% in chromatography; about 2% as a lifting gas; about 3% in other, misc applications (1975)

Cryogenic applications, 33%; Welding cover gas, 19%; Pressurizing & purging, 18%;

(1987, European) Low temperature technology, 37%; welding, 9%; pressurization and inerting, 7%; diving, 9%; chromatography, 15%; leak detection, 4%; balloons, 8%; heat exchange, 3%; artificial atmospheres, protective gases, 8%

(1997, Europe) Low temperature technology, 36%; welding, cutting, 14%; optical fibers, 8%; breathing mixtures, diving, 6%; analysis, 14%; leak detection, 9%; balloons, 7%; other uses, 6%

For more Consumption Patterns (Complete) data for HELIUM (6 total), please visit the HSDB record page.

Applications · 7 items

DescriptionHelium is a colorless, odorless, and tasteless monoatomic gas with an atomic weight of 4, a density of 1.78 g per 1 at 0°C and 1 atmosphere pressure, and an aqueous solubility of 0.97 mL per 100 mL at 50°C. The Bunsen solubility coefficient (the volume, in mL, of gas at standard conditions dissolved per mL of liquid).of helium at 38°C is 0.0086 in water, and 0.015 in olive oil. After hydrogen, helium is the most abundant element in the universe; these elements are believed to represent 76 and 23 percent, respectively, of all matter in the universe. The earth’s atmosphere, however, contains only 5 ppm of helium. Mineral gases from wells contain higher concentrations and serve as the principal source for industrial production. Helium is chemically very inert; it has a weak tendency to combine with other elements such as fluorine. It is usually marketed as compressed gas, with the USP grade containing not less than 99 percent helium.The largest biological use of helium is the replacement for nitrogen in synthetic breathing gas mixtures for divers and others working under high pressure conditions. The low solubility in body fluids compared to nitrogen decreases the danger of bends on depressurizing.

OccurrenceHelium is the 73rd most abundant element on Earth, but it is the second most abundant element in the universe, after hydrogen. Together, helium and hydrogen make up 99.9% of all the elements in the universe, but helium makes up only a small trace of the elements on Earth. Most likely, helium was the first element to be formed after hydrogen during the Big Bang formation of the universe. The theory is that hydrogen atoms combined under great heat and pressure to form helium atoms. The Earth s current helium originally came from the natural decay of radioactive elements deep in the Earth. Much of it seeps up to the surface and escapes into the atmosphere, or it mixes with natural gas deposits deep in the Earth. Like hydrogen, it is a very light gas that escapes through cracks in the Earth s crust and sooner or later escapes from Earth s gravity into the atmosphere. Helium can be obtained from the atmosphere by lowering the temperature of air until it liquefies. All the other gases in air will turn to a liquid except helium, because it has the lowest boiling point. Since helium, at this stage of cooling, will be the only vapor left, it can be removed as a pure gas. It is commercially more profitable to produce helium by separating it from a mix of natural underground gases, where its concentration is greater that in the atmosphere. Raw natural gas is a mixture of methane, nitrogen, and helium, with traces of other gases. The nitrogen and helium are separated from the methane, which is used as a fuel. This separation is accomplished by fractional distillation wherein the temperature is reduced and the gases are liquefied. As the temperature is reduced, methane is liquefied first, then nitrogen, leaving helium to be collected and sold commercially. Helium is then purified to 99.995%. Most of the world s supply of helium comes from the United States.

Historyvalence usually 0. Evidence of the existence of helium was first obtained by Janssen during the solar eclipse of 1868 when he detected a new line in the solar spectrum; Lockyer and Frankland suggested the name helium for the new element; in 1895, Ramsay discovered helium in the uranium mineral cleveite, and it was independently discovered in cleveite by the Swedish chemists Cleve and Langlet about the same time. Rutherford and Royds in 1907 demonstrated that α particles are helium nuclei. Except for hydrogen, helium is the most abundant element found throughout the universe. Helium is extracted from natural gas; all natural gas contains at least trace quantities of helium. It has been detected spectroscopically in great abundance, especially in the hotter stars, and it is an important component in both the proton–proton reaction and the carbon cycle, which account for the energy of the sun and stars. The fusion of hydrogen into helium provides the energy of the hydrogen bomb. The helium content of the atmosphere is about 1 part in 200,000. It is present in various radioactive minerals as a decay product. Much of the world’s supply of helium is obtained from wells in Texas, Colorado, and Kansas. The only other known helium extraction plants, outside the United States, in 1999 were in Poland, Russia, China, Algeria, and India. The cost of helium has fallen from $2500/ft3 in 1915 to about 2.5¢/cu.ft. (.028 cu meters) in 1999. Helium has the lowest melting point of any element and has found wide use in cryogenic research, as its boiling point is close to absolute zero. Its use in the study of superconductivity is vital. Using liquid helium, Kurti and co-workers, and others, have succeeded in obtaining temperatures of a few microkelvins by the adiabatic demagnetization of copper nuclei, starting from about 0.01 K. Liquid helium (He4) exists in two forms: He4I and He4II, with a sharp transition point at 2.174 K (3.83 cm Hg). He4I (above this temperature) is a normal liquid, but He4II (below it) is unlike any other known substance. It expands on cooling; its conductivity for heat is enormous; and neither its heat conduction nor viscosity obeys normal rules. It has other peculiar properties. Helium is the only liquid that cannot be solidified by lowering the temperature. It remains liquid down to absolute zero at ordinary pressures, but it can readily be solidified by increasingthe pressure. Solid 3He and 4He are unusual in that both can readily be changed in volume by more than 30% by application of pressure. The specific heat of helium gas is unusually high. The density of helium vapor at the normal boiling point is also very high, with the vapor expanding greatly when heated to room temperature. Containers filled with helium gas at 5 to 10 K should be treated as though they contained liquid helium due to the l

UsesHelium has many uses. As an inert gas, it is used as the atmosphere in which to “grow” silicon crystals (computerchips). As a lifting gas, it is used to inflate weather balloons and lighter-than-air ships (blimps)similar to the ones seen taking TV pictures above football games. Even though helium has lesslifting power than hydrogen, it is used for all lighter-than-air ships because it is noncombustibleand thus safer than hydrogen. In addition to blimps, toy balloons are filled with helium. In arc welding, it is used as an inert gas shield that releases great heat for very long andheavy welds. Helium prevents oxidation of the metal being welded, thus preventing burningand corrosion of the metal. This is one of the major uses of helium. Helium is used for low-temperature research (–272.2°C or –434°F). It has become importantas a coolant for superconducting electrical systems that, when cooled, offer little resistance to theelectrons passing through a conductor (wire or magnet). When the electrons are “stripped” fromthe helium atom, a positive He++ ion results. The positive helium ions (nuclei) occur in bothnatural and man-made radioactive emissions and are referred to as alpha particles. Helium ions(alpha particles) are used in high-energy physics to study the nature of matter. In gas discharge lasers, helium transfers the energy to the laser gas such as carbon dioxideor another inert gas;in mixtures with neon and argon for electronic tubes and “neon” signs.. As an inert gas with heat-transfer capability, helium is used in gas-cooled nuclear powerreactors, which operate at a higher efficiency than liquid-cooled nuclear reactors. Theworld’s largest particle accelerators use liquid helium to cool their superconducting magnets.Astronomers use liquid helium to cool their detecting instruments. If this equipment is keptcool, the “thermal noise” produced at higher temperatures is reduced.

UsesGases, diluent.

UsesHelium is used as an inert gas shield in arc welding, as a lifting gas for lighter-than-air aircraft, and as a gaseous cooling medium in nuclear reactors. It is also used to provide a protective atmosphere for growing germanium and silicon crystals for transistors, to provide a protective atmosphere in the production of such reactive metals as titanium and zirconium, to fill cold-weather fluorescent lamps, to trace leaks in refrigeration and other closed systems, and to fill neutron and gas thermometers. Its thermal conductivity makes it an important gas for lasers and fiber optic production. It is used extensively in chromatography due to its inertness and high thermal conductivity. It is used in cryogenic research such as for superconductivity. In mixtures with oxygen, it has medical and diving applications. Radioactive mixtures of helium with krypton are available to users licensed by the Nuclear Regulatory Commission. NASA uses helium for purging and pressurizing the liquid hydrogen tanks of spacecraft because it is the only element that remains a gas in the extreme cold necessary to maintain the liquid hydrogen fuel used in many rockets and the Space Shuttle. Liquid helium is used for cooling superconductive magnets, used in magnetic resonance imaging, and in magnetic separation.

General DescriptionA colorless, odorless, noncombustible gas. Can asphyxiate. Inhalation causes the voice to become squeaky (Mickey Mouse voice). Exposure of the container to prolonged heat or fire can cause HELIUM to rupture violently and rocket. If liquefied, contact of the very cold liquid with water causes violent boiling. Pressures may build to dangerous levels if the liquid contacts water in a closed container. Used in arc welding, to trace leaks in refrigeration and other closed systems and as a lifting gas for lighter-than-air aircraft.

Upstream & downstream products

Upstream raw materials

Downstream products

Additional notes · 3 items

DefinitionNoble element of atomic number 2, first element in the noble gas group of the periodic table, aw 4.00260, valence of 0. Helium nuclei are alpha particles. Most important isotope is helium-3.

DefinitionA colorless monatomic gas; the first member of the rare gases (group 18 of the periodic table). Helium has the electronic configuration 1s2 and consists of a nucleus of two protons and two neutrons (equivalent to an α- particle) with two extra-nuclear electrons. It has an extremely high ionization potential and is completely resistant to chemical attack of any sort. The gas accounts for only 5.2 × 10-4% of the atmosphere; up to 7% occurs in some natural gas deposits. Helium is the second most abundant element in the universe, the primary process on the Sun being nuclear fusion of hydrogen to give helium. Helium is recovered commercially from natural gas in both the USA and countries of the former USSR and it also forms part of ammonia plant tail gas if natural gas is used as a feedstock. Its applications are in fields in which inertness is required and where the cheaper alternatives, such as nitrogen, are too reactive; for example, high-temperature metallurgy, powder technology, and as a coolant in nuclear reactors. Helium is also favoured over nitrogen for diluting oxygen for deep-sea diving (lower solubility in blood) and as a pressurizer for liquefied gas fuels in rockets (total inertness). It is also used as an ideal gas for balloons (no fire risk) and for lowtemperature physics research. Helium is unusual in that it is the only known substance for which there is no triple point (i.e., no combination of pressure and temperature at which all three phases can co-exist). This is because the interatomic forces, which normally participate in the formation of solids, are so weak that they are of the same order as the zeropoint energy. At 2.2 K helium undergoes a transition from liquid helium I to liquid helium II, the latter being a true liquid but exhibiting superconductivity and an immeasurably low viscosity (superfluidity). The low viscosity allows the liquid to spread in layers a few atoms thick, described by some as ‘flowing uphill’. Helium also has an isotope. 3He is formed in nuclear reactions and by decay of tritium. This also undergoes a phase change at temperatures close to absolute zero. Symbol: He; m.p. 0.95 K (pressure); b.p. 4.216 K; d. 0.1785 kg m-3 (0°C); p.n. 2; r.a.m. 4.002602.

Definitionhelium: Symbol He. A colourlessodourless gaseous nonmetallic elementbelonging to group 18 of theperiodic table ; a.n.2; r.a.m. 4.0026; d. 0.178 g dm–3; m.p.–272.2°C (at 20 atm.); b.p. –268.93°C.The element has the lowest boilingpoint of all substances and can be solidifiedonly under pressure. Naturalhelium is mostly helium–4, with asmall amount of helium–3. There arealso two short-lived radioactive isotopes:helium–5 and –6. It occurs inores of uranium and thorium and insome natural-gas deposits. It has a varietyof uses, including the provisionof inert atmospheres for welding andsemiconductor manufacture, as a refrigerantfor superconductors, and asa diluent in breathing apparatus. It isalso used in filling balloons. Chemicallyit is totally inert and has noknown compounds. It was discoveredin the solar spectrum in 1868 byJoseph Lockyer (1836–1920).

Related reactions

1 records

Compound notes

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