Helium
2
He
Groep
18
Periode
1
Blok
s
Protonen
Elektronen
Neutronen
2
2
2
Algemene Eigenschappen
Atoomnummer
2
Atomair gewicht
4,002602
Massa Getal
4
Categorie
Edelgassen
Kleur
Kleurloos
Radioactief
Nee
Van het Griekse woord helios, de zon
Kristalstructuur
Zijvlak-gecentreerde Kubus
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.
Eletronen per schil
2
Electronconfiguratie
1s2
Unlike any other element, helium will remain liquid down to absolute zero at normal pressures
Fysieke Eigenschappen
Fase
Gas
Dichtheid
0,0001785 g/cm3
Smeltpunt
0,95 K | -272,2 °C | -457,96 °F
Kookpunt
4,22 K | -268,93 °C | -452,07 °F
Fusiewarmte
0,02 kJ/mol
Verdampingswarmte
0,083 kJ/mol
Specifieke Warmtecapaciteit
5,193 J/g·K
Overvloedig aanwezig in de aardkorst
5,5×10-7%
Overvloedig aanwezig in het universum
23%
CAS-nummer
7440-59-7
PubChem CID nummer
23987
Atoomeigenschappen
Atoomstraal
31 pm
Covalentiestraal
28 pm
Electronegativiteit
-
Ionisatiepotentiaal
24,5874 eV
Atoomvolume
27,2 cm3/mol
Thermische geleiding
0,00152 W/cm·K
Oxidatietoestanden
0
Toepassingen
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
Isotopen
Stabiele isotopen
3He, 4HeInstabiele isotopen
5He, 6He, 7He, 8He, 9He, 10He