Helium

Helium (He)

chemical element with symbol He and atomic number 2; rare gas
Atomic Number2
Atomic Weight4.002602
mass number4
Group18
Period1
Blocks
proton2 p+
neutron2 n0
electron2 e-
Animated Bohr model of He (Helium)

Physical Property

Atomic Radius
120 pm
molar volume
Covalent Radius
46 pm
Metallic Radius
ionic radius
Crystal Radius
Van der Waals radius
140 pm
density
0.000164 g/cm³
Atomic Radii Of The Elements: Helium0102030405060708090100110120130140pmAtomic RadiusCovalent RadiusMetallic RadiusVan der Waals radius

Chemical Property

energia
proton affinity
177.8 kJ/mol
electron affinity
ionization energy
24.587387936 eV/particle
ionization energy of He (Helium)
enthalpy of vaporization
0.08 kJ/mol
enthalpy of fusion
standard enthalpy of formation
electron
Tegimen electronicum2
Bohr model: He (Helium)
valence electron2
Lewis structure: He (Helium)
electron configuration1s2
Enhanced Bohr model of He (Helium)
Orbital Diagram of He (Helium)
oxidation number
electronegativity
Electrophilicity Index
0.0674191963846371 eV/particle
fundamental state of matter
phase of matterGas
gaseous state of matterMonoatomic
Boiling Point
4.222 K
Melting Point
critical pressure
0.22746 MPa
critical temperature
5.195 K
Punctum triplex
2.177 K
5.043 kPa
appearance
Color
Colorless
appearancecolorless 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 ratio5/3
electrical properties
type
electrical conductivity
electrical resistivity
Superconductrum
magnetism
typediamagnetic
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
structure
Crystal StructureFace Centered Cubic (HEX)
lattice constant
3.57 Å
Lattice Anglesπ/2, π/2, π/2
mechanical property
hardness
bulk modulus
shear modulus
Young's modulus
Poisson's ratio
celeritas soni
970 m/s
classificare
CategoryNoble gases, Noble gases
CAS GroupVIII
IUPAC GroupVIIIA
Glawe Number1
Mendeleev Number112
Pettifor Number1
Geochemical Classvolatile
Goldschmidt classificationatmophile

other

Gas Basicity
148.5 kJ/mol
polarizability
1.38375 ± 0.00002 a₀
C6 Dispersion Coefficient
1.42 a₀
allotrope
Neutron cross section
0.007
Neutron Mass Absorption
0.00001
quantum number1S0
space group225 (Fm_3m)

Isotopes of Helium

Stable Isotopes2
Unstable Isotopes6
Natural Isotopes2
Isotopic Composition4100.00%4100.00%30.00%30.00%

3He

mass number3
neutron number1
relative atomic mass
3.01602932197 ± 0.00000000006 Da
g-factor
-4.25525062 ± 0.00000006
natural abundance
0.0002 ± 0.0002
radioactivitasstable isotope
half-lifeNot Radioactive ☢️
Volubilitas1/2
nuclear quadrupole moment
0
repertus1934
parity+

4He

mass number4
neutron number2
relative atomic mass
4.00260325413 ± 0.00000000016 Da
g-factor
0
natural abundance
99.9998 ± 0.0002
radioactivitasstable isotope
half-lifeNot Radioactive ☢️
Volubilitas0
nuclear quadrupole moment
0
repertus1908
parity+

5He

mass number5
neutron number3
relative atomic mass
5.012057224 ± 0.00002147 Da
g-factor
natural abundance
radioactivitas☢️ radioactive element
half-life
602 ± 22 ys
Volubilitas3/2
nuclear quadrupole moment
repertus1937
parity-

decay modeintensity
n (neutron emission)100%

6He

mass number6
neutron number4
relative atomic mass
6.018885889 ± 0.000000057 Da
g-factor
0
natural abundance
radioactivitas☢️ radioactive element
half-life
806.92 ± 0.24 ms
Volubilitas0
nuclear quadrupole moment
0
repertus1936
parity+

decay modeintensity
β (β decay)100%
β d (β-delayed deuteron emission)0.000278%

7He

mass number7
neutron number5
relative atomic mass
7.027990652 ± 0.000008115 Da
g-factor
natural abundance
radioactivitas☢️ radioactive element
half-life
2.51 ± 0.07 zs
Volubilitas3/2
nuclear quadrupole moment
repertus1967
parity

decay modeintensity
n (neutron emission)100%

8He

mass number8
neutron number6
relative atomic mass
8.033934388 ± 0.000000095 Da
g-factor
0
natural abundance
radioactivitas☢️ radioactive element
half-life
119.5 ± 1.5 ms
Volubilitas0
nuclear quadrupole moment
0
repertus1965
parity+

decay modeintensity
β (β decay)100%
β n (β-delayed neutron emission)16%
β t (β-delayed triton emission)0.9%

9He

mass number9
neutron number7
relative atomic mass
9.043946414 ± 0.000050259 Da
g-factor
natural abundance
radioactivitas☢️ radioactive element
half-life
2.5 ± 2.3 zs
Volubilitas1/2
nuclear quadrupole moment
0
repertus1987
parity

decay modeintensity
n (neutron emission)100%

10He

mass number10
neutron number8
relative atomic mass
10.052815306 ± 0.000099676 Da
g-factor
0
natural abundance
radioactivitas☢️ radioactive element
half-life
260 ± 40 ys
Volubilitas0
nuclear quadrupole moment
0
repertus1994
parity+

decay modeintensity
2n (2-neutron emission)100%
Helium discharge tube

historia

inventorSir William Ramsey, Nils Langet, P.T.Cleve
location of discoveryScotland/Sweden
repertus1895
EtymologiaGreek: hêlios (sun).
pronunciationHEE-li-em (English)

source

Abundance
Abundance in Earth's crust
0.008 mg/kg
natural abundance (Oceanus)
0.000007 mg/L
natural abundance (Corpus humanum)
natural abundance (Meteoroides)
natural abundance (Sol)
23 %
Abundance in Universe
23 %

Nuclear Screening Constants

1s0.3125