Helyum (He)

chemical element with symbol He and atomic number 2; rare gas

Atomic Number	2
Atomic Weight	4.002602
mass number	4

Group	18
Period	1
Block	s

proton	2 p⁺
neutron	2 n⁰
electron	2 e^-

Physical Property

Atomic Radius	120 pm 134 pm
molar volume	31.8 cm³/mol
covalent radius	46 pm 28 pm
Metallic Radius	122 pm
ionic radius
Crystal Radius
Van der Waals radius	140 pm 140 pm 153 pm 236.2 pm
dosedh	0.000164 g/cm³

Chemical Property

nerth

proton affinity	177.8 kJ/mol
electron affinity	-19.7 eV/particle
ionization energy	24.587387936 eV/particle 54.41776311 eV/particle

enthalpy of vaporization	0.08 kJ/mol
enthalpy of fusion
standard enthalpy of formation
electron

electron shell	2

valence electron	2 ⓘ

aray an elektrons	1s²ⓘ

oxidation number
electronegativity	24.59 eV/particle 0.442712
Electrophilicity Index	0.0674191963846371 eV/particle
fundamental state of matter

phase of matter	Gas
gaseous state of matter	Monoatomic
Boiling Point	4.222 K
Melting Point
critical pressure	0.22746 MPa
critical temperature	5.195 K
triple point	2.177 K 5.043 kPa
appearance
liw	Colorless #ffc0cb #d9ffff #d9ffff
appearance	colorless gas, exhibiting a red-orange glow when placed in a high-voltage electric field
refractive index	1.000035
thermodynamic material property
Thermal Conductivity	0.152 W/(m K)
thermal expansion
molar heat capacity	20.786 J/(mol K)
Specific Heat Capacity	5.193 J/(g⋅K)
heat capacity ratio	5/3
electrical properties
type
electrical conductivity
electrical resistivity
superconductivity
magnetism
type	diamagnetic
magnetic susceptibility (Mass)	-0.0000000059 m³/Kg
magnetic susceptibility (Molar)	-0.0000000000236 m³/mol
magnetic susceptibility (Volume)	-0.00000000105
magnetic ordering
Curie temperature
Néel temperature
kesweyth
Crystal Structure	Face Centered Cubic (HEX)
lattice constant	3.57 Å
Lattice Angles	π/2, π/2, π/2
mechanical property
hardness
bulk modulus
shear modulus
Young's modulus
Poisson's ratio
speed of sound	970 m/s
classification
Category	Noble gases, Noble gases
CAS Group	VIII
IUPAC Group	VIIIA
Glawe Number	1
Mendeleev Number	112
Pettifor Number	1
Geochemical Class	volatile
Goldschmidt classification	atmophile

other

Gas Basicity	148.5 kJ/mol
polarizability	1.38375 ± 0.00002 a₀
C6 Dispersion Coefficient	1.42 a₀ 1.47 a₀
allotrope
Neutron cross section	0.007
Neutron Mass Absorption	0.00001
quantum number	1S0
space group	225 (Fm_3m)

Isotopes of Helium

Stable Isotopes	2
Unstable Isotopes	6
Natural Isotopes	2

³He

mass number	3
neutron number	1
relative atomic mass	3.01602932197 ± 0.00000000006 Da
g-factor	-4.25525062 ± 0.00000006
natural abundance	0.0002 ± 0.0002
radioactivity	stable isotope
half-life	Not Radioactive ☢️
spin	1/2
nuclear quadrupole moment	0
dydhyas diskudhans	1934
parity	+

⁴He

mass number	4
neutron number	2
relative atomic mass	4.00260325413 ± 0.00000000016 Da
g-factor	0
natural abundance	99.9998 ± 0.0002
radioactivity	stable isotope
half-life	Not Radioactive ☢️
spin	0
nuclear quadrupole moment	0
dydhyas diskudhans	1908
parity	+

⁵He

mass number	5
neutron number	3
relative atomic mass	5.012057224 ± 0.00002147 Da
g-factor
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life	602 ± 22 ys
spin	3/2
nuclear quadrupole moment
dydhyas diskudhans	1937
parity	-

decay mode	intensity
n (neutron emission)	100%

⁶He

mass number	6
neutron number	4
relative atomic mass	6.018885889 ± 0.000000057 Da
g-factor	0
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life	806.92 ± 0.24 ms
spin	0
nuclear quadrupole moment	0
dydhyas diskudhans	1936
parity	+

decay mode	intensity
β⁻ (β⁻ decay)	100%
β⁻ d (β⁻-delayed deuteron emission)	0.000278%

⁷He

mass number	7
neutron number	5
relative atomic mass	7.027990652 ± 0.000008115 Da
g-factor
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life	2.51 ± 0.07 zs
spin	3/2
nuclear quadrupole moment
dydhyas diskudhans	1967
parity

decay mode	intensity
n (neutron emission)	100%

⁸He

mass number	8
neutron number	6
relative atomic mass	8.033934388 ± 0.000000095 Da
g-factor	0
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life	119.5 ± 1.5 ms
spin	0
nuclear quadrupole moment	0
dydhyas diskudhans	1965
parity	+

decay mode	intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	16%
β⁻ t (β⁻-delayed triton emission)	0.9%

⁹He

mass number	9
neutron number	7
relative atomic mass	9.043946414 ± 0.000050259 Da
g-factor
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life	2.5 ± 2.3 zs
spin	1/2
nuclear quadrupole moment	0
dydhyas diskudhans	1987
parity

decay mode	intensity
n (neutron emission)	100%

¹⁰He

mass number	10
neutron number	8
relative atomic mass	10.052815306 ± 0.000099676 Da
g-factor	0
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life	260 ± 40 ys
spin	0
nuclear quadrupole moment	0
dydhyas diskudhans	1994
parity	+

decay mode	intensity
2n (2-neutron emission)	100%

istori

diskudher po dismyger	Sir William Ramsey, Nils Langet, P.T.Cleve
location of discovery	Scotland/Sweden
dydhyas diskudhans	1895
Etymologyl	Greek: hêlios (sun).
pronunciation	HEE-li-em (en)

source

Abundance
Abundance in Earth's crust	0.008 mg/kg
natural abundance (Keynvor)	0.000007 mg/L
natural abundance (Korf)
natural abundance (meteoroid)
natural abundance (Howl)	23 %
Abundance in Universe	23 %

Nuclear Screening Constants

0.3125

Helyum on ChemicalAid

ATC code	V03AN03
Australian Educational Vocabulary ID	scot/3528
BNCF Thesaurus ID	19752
Bibliothèque nationale de France ID	11978648w
Brockhaus Enzyklopädie online ID	helium-20
CAB ID	178029
CAS Registry Number	7440-59-7
ChEBI ID	30217
ChEMBL ID	CHEMBL1796997
ChemSpider ID	22423
Common Procurement Vocabulary	24111300
DSSTOX compound identifier	DTXCID5016402
DSSTox substance ID	DTXSID7036402
De Agostini ID	èlio
Den Store Danske ID	helium
DrugBank ID	09155
ECHA Substance Infocard ID	100.028.334
Encyclopædia Britannica Online ID	science/helium-chemical-element
Encyclopædia Universalis ID	helium
E number	E939
Freebase ID	/m/025rt79
French Vikidia ID	Hélium
Golden ID	Helium-K8NB
Great Russian Encyclopedia Online ID	2348591
HSDB ID	553
ICSC ID	0603
InChI	InChI=1S/He
InChIKey	SWQJXJOGLNCZEY-UHFFFAOYSA-N
Italian Vikidia ID	Elio
KBpedia ID	Helium
Klexikon article ID	Helium
Krugosvet article	nauka_i_tehnika/himiya/GELI.html
Library of Congress authority ID	sh85060043
MeSH descriptor ID	D006371
Mindat mineral ID	25563
NALT ID	44987
NDF-RT ID	N0000147379
NDL Authority ID	00563132
NE.se ID	helium
NKCR AUT ID	ph503003
Namuwiki ID	헬륨
National Library of Israel J9U ID	987007555644805171
OmegaWiki Defined Meaning	7296
Online PWN Encyclopedia ID	3910758
OpenAlex ID	C546029482
OpenAlex ID	C2991909631
PSH ID	5816
Probes And Drugs ID	PD009020
PubChem CID	23987
Quora topic ID	Helium
RxNorm ID	5140
Römpp online ID	RD-08-00783
Spanish Vikidia ID	Helio
Store norske leksikon ID	helium
Treccani ID	elio
U.S. National Archives Identifier	10640583
UMLS CUI	C0018880
UNII	206GF3GB41
USGS Thesaurus ID	1470
WordNet 3.1 Synset ID	14664099-n
World of Physics ID	Helium
YSO ID	14499
ZVG number	7020
honanieth GND	4132459-6

Helyum (He)

Physical Property

Chemical Property

other

Isotopes of Helium

3He

4He

5He

6He

7He

8He

9He

10He

istori

source

Nuclear Screening Constants

³He

⁴He

⁵He

⁶He

⁷He

⁸He

⁹He

¹⁰He