Helium
2
He
Gruppe
18
Periode
1
Blokk
s
Protons
Electrons
Neutrons
2
2
2
Generelle eigenskapar
Atomnummer
2
Atommasse
4,002602
Mass Number
4
Kategori
Edelgassar
Farge
Fargelaus
Radioactive
Nei
From the Greek word helios, the sun
Krystallstruktur
Face Centered Cubic
Historie
French astronomer Jules Janssen obtained the first evidence of helium during the solar eclipse of 1868.
Norman Lockyer and Edward Frankland suggested the name helium for the new element.
In 1895, Sir William Ramsay discovered helium in the uranium mineral cleveite.
It was independently discovered in cleveite by Per Teodor Cleve and Abraham Langlet.
Norman Lockyer and Edward Frankland suggested the name helium for the new element.
In 1895, Sir William Ramsay discovered helium in the uranium mineral cleveite.
It was independently discovered in cleveite by Per Teodor Cleve and Abraham Langlet.
Elektron per energinivå
2
Elektronkonfigurasjon
1s2
Unlike any other element, helium will remain liquid down to absolute zero at normal pressures
Fysiske eigenskapar
Tilstandsform
Gass
Tettleik
0,0001785 g/cm3
Smeltepunkt
0,95 K | -272,2 °C | -457,96 °F
Kokepunkt
4,22 K | -268,93 °C | -452,07 °F
Smeltevarme
0,02 kJ/mol
Fordampingsvarme
0,083 kJ/mol
Spesifikk varmekapasitet
5,193 J/g·K
Abundance in Earth's crust
5,5×10-7%
Abundance in Universe
23%
CAS Number
7440-59-7
PubChem CID Number
23987
Atom eigenskapar
Atomradius
31 pm
Kovalent radius
28 pm
Elektronegativitet
-
Ioniseringspotensial
24,5874 eV
Molart volum
27,2 cm3/mol
Termisk konduktivitet
0,00152 W/cm·K
Oksidasjonstrinn
0
Applications
Helium is used as a protective gas in growing silicon and germanium crystals, in titanium and zirconium production, and in gas chromatography.
Helium at low temperatures is used in cryogenics.
Helium is used for filling balloons and for pressurizing liquid fuel rockets.
Helium is used as a shielding gas in arc welding processes.
Helium at low temperatures is used in cryogenics.
Helium is used for filling balloons and for pressurizing liquid fuel rockets.
Helium is used as a shielding gas in arc welding processes.
Helium is not known to be toxic
Isotopes
Stable Isotopes
3He, 4HeUnstable Isotopes
5He, 6He, 7He, 8He, 9He, 10He