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hydrogen – helium
 
He
Ne  
 
 

General
Name, Symbol, Number Helium, He, 2
Atomic weight 4.002602
Chemical series Noble gases
Group, Period, Block 18 (VIIIA), 1, p
DensityFor other meanings of density, see density (disambiguation Density (symbol: rho Greek: rho) is a measure of mass per unit of volume. The higher an object's density, the higher its mass per volume. The average density of an object equals its total mass div (0° CThe degree Celsius (°C) is a unit of temperature named after the Swedish astronomer Anders Celsius ( 1701 1744), who first proposed it in 1742. The Celsius temperature scale was designed so that the freezing point of water is 0 degrees, and the boiling po, 1 atmWhen expressed as a measurement, an atmosphere is a unit of pressure based on the average atmospheric pressure at sea level on the earth. 1 atm : 101325 Pa 101325 kg/ m· s² 101325 N/ m² : 1013. 25 hPa 1013. 25 mbar : 101. 325 kPa : 1. 01325 bar : 760 torr) 0.179 gFor other meanings of gram see gram (disambiguation). The gram (also spelt gramme is a unit of measurement of mass, and is defined in the SI system of units as one thousandth of a kilogram. See 1 E -3 kg for comparisons with other masses. The symbol for g/ LThe litre (or liter in US) is a metric unit of volume. The litre is not an SI unit, but is "accepted for use with the International System". The symbol for the litre is the lowercase letter l or the uppercase letter L . A cursive or script small letter l
AppearanceFor alternative meanings, see color (disambiguation). visual arts. Color (or colour is a sensation which (in humans) derives from the ability of the fine structure of the eye to distinguish three differently filtered analyses of a view. The perception of colorless
ThermalCommonly, heat is estrus, a period of increased sexual drive in female mammals. For the National Basketball Association team, see Miami Heat. For the movie, see Heat (movie). Heat (abbreviated Q also called heat change is the transfer of thermal energy be data
Melting pointThe melting point of a solid is the temperature at which it changes state from solid to liquid. When considered as the temperature of the reverse change, it is referred to as the freezing point . For example, the melting point of the element mercury is 23 (at 26 atmWhen expressed as a measurement, an atmosphere is a unit of pressure based on the average atmospheric pressure at sea level on the earth. 1 atm : 101325 Pa 101325 kg/ m· s² 101325 N/ m² : 1013. 25 hPa 1013. 25 mbar : 101. 325 kPa : 1. 01325 bar : 760 torr) 0.95 K (-272.2° C)
Boiling point 4.22 K (-268.93° C)
Specific heat capacity 5193 J/( kg* K)
Thermal conductivity 0.152 W/( m* K)
Heat of vaporization 0.0845 kJ/ mol
Heat of fusion 5230 J/ mol
Electronic data
Electron configuration 1 s2
Electrons per shell 2
Valence 0
1st ionization potential 2372.3 kJ/ mol
2nd ionization potential 5250.5 kJ/ mol
Steric data
Covalent radius 32 pm
van der Waals radius 140 pm
Molar volume 21.0 ×10-6 m3/ mol
Crystal structure hexagonal
Isotopes
iso abundance half-life DM DE M eV DP
3He 0.000137% Stable with 1 neutron
4He 99.999863% Stable with 2 neutrons
6He synthetic 806.7 ms β- 3.508 6 Li
Except where noted, all data was produced under conditions of standard temperature and pressure.

Helium is a colorless, odorless, tasteless chemical element, one of the noble gases of the periodic table of elements. Its boiling and melting points are the lowest among the elements; except in extreme conditions, it exists only as a gas. The second most abundant element in the universe, significant amounts are found on Earth only in natural gas. It is used in cryogenics, in deep-sea breathing systems, for inflating balloons, and as a protective gas for many purposes. Helium is not toxic and has no immediate biological effect except possible harm through oxygen deprivation.



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Helium Gas Element Decay Earth Natural Oxygen Elements Universe

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HeliumHelium is a colorless, odorless, tasteless chemical element, one of the noble gases of the periodic table of elements. Its boiling and melting points are the lowest among the elements; except in extreme conditions, it exists only as a gas. The second mostHelium-3Helium-3 is a non- radioactive and light isotope of helium. It has two protons but only one neutron in contrast to two neutrons in ordinary helium. Helium-3 is rare on Earth and sought-after for use in fusion. More abundant helium-3 is thought to exist onHelium fusionHelium fusion is a kind of nuclear fusion, the two involved nuclei being helium. If the central temperature of a star exceeds 100 million Kelvin, as may happen in the later phase of red giants and red supergiants, then helium can fuse to form beryllium an
Helium burningHelium burning or the fusion of helium, requires very high temperatures, to the point where a state of electron degeneration must exist. Only then can helium fusion occur. The triple-alpha process of the fusion produces carbon and occasionally the carbonHelium-neon laserA helium-neon laser usually called a HeNe laser is a small gas laser of a type often used in laboratory demonstrations of optics. Its usual operation wavelength is 632. 8 nm, in the red portion of the visible spectrum. Schematic diagram of a helium-neon lHelium-4Helium-4 is a non- radioactive and light isotope of helium. It is by far the most abundant of the two naturally-occurring isotopes of helium, making up about 99. 99986% of the helium on earth. Its nucleus is an alpha particle, having two protons and two n


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