Helium
2
He
Gruppe
18
Periode
1
Blok
s
Protoner
Elektroner
Neutroner
2
2
2
Generelle Egenskaber
Atomnummer
2
Atommasse
4,002602
Masseantal
4
Kategori
Ædelgasser
Farve
Farveløs
Radioaktiv
Nej
From the Greek word helios, the sun
Krystalstruktur
Fladecentreret Kubisk
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.
Elektroner i hver skal
2
Elektronkonfiguration
1s2
Unlike any other element, helium will remain liquid down to absolute zero at normal pressures
Fysiske Egenskaber
Tilstandsform
Gas
Massefylde
0,0001785 g/cm3
Smeltepunkt
0,95 K | -272,2 °C | -457,96 °F
Kogepunkt
4,22 K | -268,93 °C | -452,07 °F
Smeltevarme
0,02 kJ/mol
Fordampningsvarme
0,083 kJ/mol
Varmefylde
5,193 J/g·K
Forekomst i jordskorpen
5,5×10-7%
Forekomst i universet
23%
CAS-nummer
7440-59-7
PubChem CID-nummer
23987
Atomare egenskaber
Atomradius
31 pm
Kovalent radius
28 pm
Elektronegativitet
-
Ioniseringspotentiale
24,5874 eV
Atomvolumen
27,2 cm3/mol
Varmeledningsevne
0,00152 W/cm·K
Oxidationstrin
0
Anvendelser
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
Isotoper
Stabile isotoper
3He, 4HeUstabile isotoper
5He, 6He, 7He, 8He, 9He, 10He