Helium
General:
Name: Helium
Type: Noble Gas
Density @ 293 K: 0.0001787 g/cm3
Type: Noble Gas
Density @ 293 K: 0.0001787 g/cm3
Symbol: He
Atomic weight: 4.00260
Atomic volume: 27.2 cm3/mol
Atomic weight: 4.00260
Atomic volume: 27.2 cm3/mol
States
State (s, l, g): gas
Melting point: 0.95 K (-272.2 oC)
Melting point: 0.95 K (-272.2 oC)
Boiling point: 4.2 K (-268.9 oC)
Appearance
Structure: usually hexagonal close-packed (v.high pressure needed to solidify helium)
Hardness: mohs
Hardness: mohs
Color: colorless
Harmful effects:
Helium is not known to be toxic.
Reactions & Compounds
Reaction with air: none
Reaction with 3 M HNO3: none
Oxide(s): none
Hydride(s): none
Reaction with 3 M HNO3: none
Oxide(s): none
Hydride(s): none
Reaction with 6 M HCl: none
Reaction with 6 M NaOH: none
Chloride(s): none
Reaction with 6 M NaOH: none
Chloride(s): none
Radius
Atomic radius: 31 pm
Ionic radius (2+ ion): pm
Ionic radius (2- ion): pm
Ionic radius (2+ ion): pm
Ionic radius (2- ion): pm
Ionic radius (1+ ion): pm
Ionic radius (3+ ion): pm
Ionic radius (1- ion): pm
Ionic radius (3+ ion): pm
Ionic radius (1- ion): pm
Conductivity
Thermal conductivity: 0.15 W m-1 K-1
Electrical conductivity: S cm-1
Energies
Specific heat capacity: 5.193 J g-1 K-1
Heat of fusion: 0.0138 kJ mol-1
1st ionization energy: 2372.3 kJ mol-1
3rd ionization energy: kJ mol-1
Heat of fusion: 0.0138 kJ mol-1
1st ionization energy: 2372.3 kJ mol-1
3rd ionization energy: kJ mol-1
Heat of atomization: 0
Heat of vaporization: 0.0845 kJ mol-1
3rd ionization energy: kJ mol-1
Electron affinity: 0 kJ mol-1
Heat of vaporization: 0.0845 kJ mol-1
3rd ionization energy: kJ mol-1
Electron affinity: 0 kJ mol-1
Oxidation & Electrons
Shells: 2
Minimum oxidation number: 0
Min. common oxidation no.: 0
Electronegativity (Pauling Scale):
Minimum oxidation number: 0
Min. common oxidation no.: 0
Electronegativity (Pauling Scale):
Electron configuration: 1s2
Maximum oxidation number: 0
Max. common oxidation no.: 0
Polarizability volume: 0.198 Å3
Maximum oxidation number: 0
Max. common oxidation no.: 0
Polarizability volume: 0.198 Å3
characteristics:
Helium is a light, odorless, colorless, inert monatomic gas. It can form diatomic molecules, but only weakly and at temperatures near absolute zero.
Helium has a melting point of the lowest of any element and its boiling point is close to absolute zero.
Unlike any other element, helium does not solidify but remains liquid to absolute zero (0 K) at pressures common.
The voice of someone who has inhaled helium temporarily sounds sharp.
uses:
Helium is used to fill balloons (blimps) and for pressurizing liquid fuel rockets.
Mixtures of helium and oxygen are used as an artificial "air" for divers and others working under pressure. Helium is used in place of nitrogen in normal air, for after a long dive, helium leaves the body faster than nitrogen, allowing rapid decompression.
Helium is used as a shield gas in the vicinity of arc welding and cryogenics, prevention, for example, no reaction of hot metal welding with oxygen. The gas is used in the semiconductor industry condictor to provide an inert atmosphere for crystal silicon and germanium growing. It is also used as a high temperature gas in the production of titanium and zirconium, and as a carrier gas in gas chromatography.
By virtue of its very low temperatures, liquid helium is used to produce superconductivity in certain metals shares.
Helium is a light, odorless, colorless, inert monatomic gas. It can form diatomic molecules, but only weakly and at temperatures near absolute zero.
Helium has a melting point of the lowest of any element and its boiling point is close to absolute zero.
Unlike any other element, helium does not solidify but remains liquid to absolute zero (0 K) at pressures common.
The voice of someone who has inhaled helium temporarily sounds sharp.
uses:
Helium is used to fill balloons (blimps) and for pressurizing liquid fuel rockets.
Mixtures of helium and oxygen are used as an artificial "air" for divers and others working under pressure. Helium is used in place of nitrogen in normal air, for after a long dive, helium leaves the body faster than nitrogen, allowing rapid decompression.
Helium is used as a shield gas in the vicinity of arc welding and cryogenics, prevention, for example, no reaction of hot metal welding with oxygen. The gas is used in the semiconductor industry condictor to provide an inert atmosphere for crystal silicon and germanium growing. It is also used as a high temperature gas in the production of titanium and zirconium, and as a carrier gas in gas chromatography.
By virtue of its very low temperatures, liquid helium is used to produce superconductivity in certain metals shares.
Abundance & Isotopes
Abundance earth's crust: 8 parts per billion by weight, 43 parts per billion by moles
Abundance solar system: 23 % by weight, 7.4 % by moles
Cost, pure: $5.2 per 100g
Cost, bulk: $ per 100g
Source: Nearly all the helium on Earth is the result of radioactive decay. The major sources of helium are from natural gas deposits in wells in Texas, Oklahoma and Kansas. Helium is extracted by fractional distillation of the natural gas, which contains up to 7% helium.
Isotopes: Helium has 8 isotopes whose half-lives are known, with mass numbers 3 to 10. Of these two are stable, 3He and 4He. Over 99.999% of naturally occurring helium is in the form of 4He.
Abundance solar system: 23 % by weight, 7.4 % by moles
Cost, pure: $5.2 per 100g
Cost, bulk: $ per 100g
Source: Nearly all the helium on Earth is the result of radioactive decay. The major sources of helium are from natural gas deposits in wells in Texas, Oklahoma and Kansas. Helium is extracted by fractional distillation of the natural gas, which contains up to 7% helium.
Isotopes: Helium has 8 isotopes whose half-lives are known, with mass numbers 3 to 10. Of these two are stable, 3He and 4He. Over 99.999% of naturally occurring helium is in the form of 4He.
Discovery of helium
The story of the discovery of helium is intertwined with the discovery of the nature of the stars.
At one time people thought we would never know what stars are made. In 1835, Auguste Comte said, "we can never, by any means to study their chemical composition." He thought we could only learn this star-stuff was if we could enter the laboratory.
Despite the pessimism of Comte, the method for the discovery of helium and the compositions of the stars had been found. In 1814, Joseph Fraunhofer had taken the method of Isaac Newton split sunlight with a prism and made a crucial advance. Fraunhofer noticed dark lines in the sky colors from the sun split by a prism, the lines he saw was the first ever observation of spectrum of a star.
In 1859-1860 Gustav Kirchhoff and Robert Bunsen has made huge leaps in the science of spectroscopy, including the discovery that the black lines of Fraunhofer saw was like a footprint of substance.
The stage was set for Kirchhoff and Bunsen discover new elements by studying the light from substances when burned. In 1860, they discovered cesium in its spectral lines blue and rubidium in 1861 from two spectral lines red. Then William Crookes discovered thallium in 1861 after observing a bright green line of the spectrum.
Kirchhoff and Bunsen looked spectrum of the sun and were able to conclude that iron is present in the atmosphere glowing.
For the discovery of helium, a few more years were needed. In August 1868, the first total eclipse since the work of Kirchhoff and Bunsen had been published was due. Pierre Janssen was waiting for an eclipse to observe prominences in the solar corona using a spectroscope. Within two weeks of Janssen Eclipse has developed a method of recording spectra protuberances ", without the need of an eclipse. In these spectra, it was a yellow line.
The name of the helium comes from the Greek word for sun, Helios.
Lockyer and Frankland Edward, his colleague, had a number of other ideas on the possible causes of the yellow line and did not announce a new element.
In 1871, scientists from other knew of the situation. Lord Kelvin, discussed "reflection of the bright light of hydrogen and" helium "around the sun." The use of "helium" is followed by a note to explain:
"Frankland and Lockyer find the yellow prominences to give a very bright line decided not far from D, but hitherto not identified with an earthly flame. It seems to indicate a new substance, which they propose to called helium. "
The story of the discovery of helium is intertwined with the discovery of the nature of the stars.
At one time people thought we would never know what stars are made. In 1835, Auguste Comte said, "we can never, by any means to study their chemical composition." He thought we could only learn this star-stuff was if we could enter the laboratory.
Despite the pessimism of Comte, the method for the discovery of helium and the compositions of the stars had been found. In 1814, Joseph Fraunhofer had taken the method of Isaac Newton split sunlight with a prism and made a crucial advance. Fraunhofer noticed dark lines in the sky colors from the sun split by a prism, the lines he saw was the first ever observation of spectrum of a star.
In 1859-1860 Gustav Kirchhoff and Robert Bunsen has made huge leaps in the science of spectroscopy, including the discovery that the black lines of Fraunhofer saw was like a footprint of substance.
The stage was set for Kirchhoff and Bunsen discover new elements by studying the light from substances when burned. In 1860, they discovered cesium in its spectral lines blue and rubidium in 1861 from two spectral lines red. Then William Crookes discovered thallium in 1861 after observing a bright green line of the spectrum.
Kirchhoff and Bunsen looked spectrum of the sun and were able to conclude that iron is present in the atmosphere glowing.
For the discovery of helium, a few more years were needed. In August 1868, the first total eclipse since the work of Kirchhoff and Bunsen had been published was due. Pierre Janssen was waiting for an eclipse to observe prominences in the solar corona using a spectroscope. Within two weeks of Janssen Eclipse has developed a method of recording spectra protuberances ", without the need of an eclipse. In these spectra, it was a yellow line.
The name of the helium comes from the Greek word for sun, Helios.
Lockyer and Frankland Edward, his colleague, had a number of other ideas on the possible causes of the yellow line and did not announce a new element.
In 1871, scientists from other knew of the situation. Lord Kelvin, discussed "reflection of the bright light of hydrogen and" helium "around the sun." The use of "helium" is followed by a note to explain:
"Frankland and Lockyer find the yellow prominences to give a very bright line decided not far from D, but hitherto not identified with an earthly flame. It seems to indicate a new substance, which they propose to called helium. "
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