Ħiljum, ²Elju

Ħiljum, ²Elju (He)

element kimiku bis-simbolu He u bin-numru atomiku 2
Atomic Number2
Atomic Weight4.002602
mass number4
Group18
Period1
Blocks
proton2 p+
neutron2 n0
elettron2 e-
Animated Bohr model of He (Ħiljum, ²Elju)

Physical Property

Atomic Radius
120 pm
molar volume
covalent radius
46 pm
Metallic Radius
ionic radius
Crystal Radius
Van der Waals radius
140 pm
densità
0.000164 g/cm³
Atomic Radii Of The Elements: Ħiljum, ²Elju0102030405060708090100110120130140pmAtomic RadiusCovalent RadiusMetallic RadiusVan der Waals radius

Chemical Property

enerġija
proton affinity
177.8 kJ/mol
electron affinity
ionization energy
24.587387936 eV/particle
ionization energy of He (Ħiljum, ²Elju)
enthalpy of vaporization
0.08 kJ/mol
enthalpy of fusion
standard enthalpy of formation
elettron
electron shell2
Bohr model: He (Ħiljum, ²Elju)
valence electron2
Lewis structure: He (Ħiljum, ²Elju)
electron configuration1s2
Enhanced Bohr model of He (Ħiljum, ²Elju)
Orbital Diagram of He (Ħiljum, ²Elju)
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
triple point
2.177 K
5.043 kPa
appearance
kulur
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
superconductivity
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
speed of sound
970 m/s
classification
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
radioactivitystable isotope
half-lifeNot Radioactive ☢️
spin1/2
nuclear quadrupole moment
0
time of discovery or invention1934
parity+

4He

mass number4
neutron number2
relative atomic mass
4.00260325413 ± 0.00000000016 Da
g-factor
0
natural abundance
99.9998 ± 0.0002
radioactivitystable isotope
half-lifeNot Radioactive ☢️
spin0
nuclear quadrupole moment
0
time of discovery or invention1908
parity+

5He

mass number5
neutron number3
relative atomic mass
5.012057224 ± 0.00002147 Da
g-factor
natural abundance
radioactivity☢️ radioactive element
half-life
602 ± 22 ys
spin3/2
nuclear quadrupole moment
time of discovery or invention1937
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
radioactivity☢️ radioactive element
half-life
806.92 ± 0.24 ms
spin0
nuclear quadrupole moment
0
time of discovery or invention1936
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
radioactivity☢️ radioactive element
half-life
2.51 ± 0.07 zs
spin3/2
nuclear quadrupole moment
time of discovery or invention1967
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
radioactivity☢️ radioactive element
half-life
119.5 ± 1.5 ms
spin0
nuclear quadrupole moment
0
time of discovery or invention1965
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
radioactivity☢️ radioactive element
half-life
2.5 ± 2.3 zs
spin1/2
nuclear quadrupole moment
0
time of discovery or invention1987
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
radioactivity☢️ radioactive element
half-life
260 ± 40 ys
spin0
nuclear quadrupole moment
0
time of discovery or invention1994
parity+

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

storja

discoverer or inventorSir William Ramsey, Nils Langet, P.T.Cleve
location of discoveryScotland/Sweden
time of discovery or invention1895
etimoloġijaGreek: hêlios (sun).
pronunciationHEE-li-em (Ingliż)

source

Abundance
Abundance in Earth's crust
0.008 mg/kg
natural abundance (ocean)
0.000007 mg/L
natural abundance (human body)
natural abundance (meteoroid)
natural abundance (Xemx)
23 %
Abundance in Universe
23 %

Nuclear Screening Constants

1s0.3125