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physical object > natural object > particle > element > column grouped element > inert gas > helium > helium 8

helium 8 (8He)
subject			fact

helium 8	has symbol 8He
	has nuclear spin I = 0+
	has decay mode β- (14 Mev)
	has decay mode β- n
	has decay mode γ
	has half life 0.119 seconds
	has number of nucleons 8
	has number of neutrons 6
	has atomic mass 8.03392
	is an instance of helium
helium	has stable isotope helium 3, helium 4
	has lethal intake non-toxic
	has reserves 3.7 × 109 tonnes in Earth's atmosphere
	has mineral present in some minerals
	has neutron scattering length 0.326 × 10-12 cm
	has electron affinity 0.0 kJ mol-1 from to -
	has toxic intake non-toxic
	has mass magnetic susceptibility -5.9 × 10-9 kg-1 m3 for gas
	has van der Waals radii 120 pm
	has thermal neutron capture cross section 0.007 barns
	has longest lived isotope helium 4
	has isotope mass range 3 to 8 except 7
	has number of isotopes 5 including nuclear isomers
	has pronunciation heel-iuhm
	has name origin helios = sun from Greek
	has discovery location England
	has abundance 6.31 × 1010 in Sun relative to H = 1 × 1012
	has abundance 0.008 p.p.m. in Earth's crust
	has abundance 5.2 p.p.m. by volume in Earth's atmosphere
	has abundance 4 × 10-6 p.p.m. in seawater
	has specimen small pressurized canisters. Safe.
	has world production 4500 tonnes year-1
	has chief source natural gas which may contain up to 7% helium
	has mass absorption coefficient 0.383 cm2 g-1 for CuKα X-ray diffraction
	has mass absorption coefficient 0.207 cm2 g-1 for MoKα X-ray diffraction
	has space group P63/mmc for α-He at 1.15 K, 6.69 MPa
	has space group Fm3m for β-He at 16K, 127 MPa
	has space group Im3m for γ-He at 1.73 K, 2.94 MPa
	has crystal cell dimension a = 353.1, c = 569.3 pm for α-He at 1.15 K, 6.69 MPa
	has crystal cell dimension a = 424.0 pm for β-He at 16K, 127 MPa
	has crystal cell dimension a = 411 pm for γ-He at 1.73 K, 2.94 MPa
	has crystal type h.c.p. for α-He at 1.15 K, 6.69 MPa
	has crystal type f.c.c. for β-He at 16K, 127 MPa
	has crystal type b.c.c. for γ-He at 1.73 K, 2.94 MPa
	has atomic emission line 388.865 nm for He I
	has atomic emission line 587.562 nm for He I
	has atomic emission line 1083.025 nm for He I
	has atomic emission line 1083.034 nm for He I (strong)
	has atomic emission line 1868.534 nm for He I
	has atomic emission line 2058.130 nm for He I
	has term symbol 1S0 in ground state
	has electron configuration 1s2 = [He] in ground state
	has mass of element in person very small for a 70 kg average person
	has daily dietary intake very low
	has level in humans traces
	has hazard harmless but could asphyxiate if it excludes oxygen from the lungs
	has biological role none
	has thermal conductivity 0.152 W m-1 K-1 at 300 K
	has molar volume 32.07 cm3 at 4 K
	has heat capacity 20.786 J K-1 mol-1 for gas at constant pressure 0.1 MPa at 298.15 K
	has heat of vaporization 0.082 kJ mol-1
	has heat of fusion 0.021 kJ mol-1
	has boiling point 4.216 K
	has melting point 0.95 K under pressure
	has relative atomic mass 4.005602 in units of 12C = 12.000
	has atomic radii 128 pm
	has number of protons 2
	has registry number 7440-59-7 for Chemical Abstracts System database
	has density 124.8 kg m-3 for liquid at 4.216 K boiling point
	has density 0.1785 kg m-3 for gas at 273 K
	has synthesis mechanism
	has ocean oxidation state 0
	has atomic number 2
	reacts with nothing
has discovery date 1868
has discoverer Norman Lockyer and Edward Frankland
has uses deep-sea diving, weather baloons, low temperature research
has image
has critical pressure 229 kPa
has critical temperature 5.25 K
unclassified oceanic element	has ocean residence time unknown
	has ocean concentration unknown
inert gas	has group 18
	has synonym group VIII element
	has synonym noble gas
element	is a part of Universe
oceanic element	has occurrence ocean
atmophile element	has occurrence atmosphere of a planet or asteroid
gaseous element	has state gas at standard temperature and pressure
particle	obeys uncertainty principle
	has frequency inversely proportional to the wavelength
	has wavelength inversely proportional to its momentum
	has charge
	has mass
physical object	has location or center of gravity
	has angular momentum
	has velocity
	has momentum
	has temperature
	has volume
	has extent
	has material

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