Helium
2
He
Gruppe
18
Periode
1
Block
s
Protonen
Elektronen
Neutronen
2
2
2
Generelle Eigenschaften
Ordnungszahl
2
Atommasse
4,002602
Massenzahl
4
Kategorie
Edelgase
Farbe
Farblos
Radioaktiv
Nein
Aus dem Griechischen helios (Sonne)
Kristallstruktur
Kubisch flächenzentriert
Geschichte
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.
Elektronen pro Schale
2
Elektronenkonfiguration
1s2
Unlike any other element, helium will remain liquid down to absolute zero at normal pressures
Physikalische Eigenschaften
Aggregatzustand
Gasförmig
Dichte
0,0001785 g/cm3
Schmelzpunkt
0,95 K | -272,2 °C | -457,96 °F
Siedepunkt
4,22 K | -268,93 °C | -452,07 °F
Schmelzwärme
0,02 kJ/mol
Verdampfungswärme
0,083 kJ/mol
Spezifische Wärmekapazität
5,193 J/g·K
Häufigkeit in der Erdkruste
5,5×10-7%
Häufigkeit im Universum
23%
CAS-Nummer
7440-59-7
PubChem CID-Nummer
23987
Atomeigenschaften
Atomradius
31 pm
Kovalenter Radius
28 pm
Elektronegativität
-
Ionisierungsenergie
24,5874 eV
Molares Volumen
27,2 cm3/mol
Wärmeleitfähigkeit
0,00152 W/cm·K
Oxidationszustände
0
Anwendung
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
Isotope
Stabile Isotope
3He, 4HeInstabile Isotope
5He, 6He, 7He, 8He, 9He, 10He