2 – Helium, He
2 – Helium, He
2 – Helium, He
2 – Helium, He
2 – Helium, He
Helium is a monoatomic, colourless and inert gas and is the second lightest chemical element with the lowest boiling and melting points.
Helium is a monoatomic, colourless and inert gas and is the second lightest chemical element with the lowest boiling and melting points.
Helium is a monoatomic, colourless and inert gas and is the second lightest chemical element with the lowest boiling and melting points.
Helium is a monoatomic, colourless and inert gas and is the second lightest chemical element with the lowest boiling and melting points.
Helium is a monoatomic, colourless and inert gas and is the second lightest chemical element with the lowest boiling and melting points.
1868 by Pierre Janssen and Norman Lockyer.
1868 by Pierre Janssen and Norman Lockyer.
1868 by Pierre Janssen and Norman Lockyer.
1868 by Pierre Janssen and Norman Lockyer.
1868 by Pierre Janssen and Norman Lockyer.
DISCOVERY
DISCOVERY
DISCOVERY
DISCOVERY
DISCOVERY
Ancient Greek, hḗlios, 'sun'.
Ancient Greek, hḗlios, 'sun'.
Ancient Greek, hḗlios, 'sun'.
Ancient Greek, hḗlios, 'sun'.
Ancient Greek, hḗlios, 'sun'.
ETYMOLOGY
ETYMOLOGY
ETYMOLOGY
ETYMOLOGY
ETYMOLOGY
Helium
Helium
Helium
Helium
Helium
Element
Element
Element
Element
Element
He
He
He
He
He
Symbol
Symbol
Symbol
Symbol
Symbol
2
2
2
2
2
Atomic Number
Atomic Number
Atomic Number
Atomic Number
Atomic Number
Noble Gas
Noble Gas
Noble Gas
Noble Gas
Noble Gas
Classification
Classification
Classification
Classification
Classification
7440-59-7
7440-59-7
7440-59-7
7440-59-7
7440-59-7
CAS Number
CAS Number
CAS Number
CAS Number
CAS Number
Colourless
Colourless
Colourless
Colourless
Colourless
Elemental Colour
Elemental Colour
Elemental Colour
Elemental Colour
Elemental Colour
1.000'035
1.000'035
1.000'035
1.000'035
1.000'035
Refractive Index
Refractive Index
Refractive Index
Refractive Index
Refractive Index
-
-
-
-
-
Poisson Ratio
Poisson Ratio
Poisson Ratio
Poisson Ratio
Poisson Ratio
22.424 cm3
22.424 cm3
22.424 cm3
22.424 cm3
22.424 cm3
Molar Volume
Molar Volume
Molar Volume
Molar Volume
Molar Volume
-
-
-
-
-
Brinell Hardness
Brinell Hardness
Brinell Hardness
Brinell Hardness
Brinell Hardness
-
-
-
-
-
Mohs Hardness
Mohs Hardness
Mohs Hardness
Mohs Hardness
Mohs Hardness
-
-
-
-
-
Vickers Hardness
Vickers Hardness
Vickers Hardness
Vickers Hardness
Vickers Hardness
970 m/s, Mach 2.828'0
970 m/s, Mach 2.828'0
970 m/s, Mach 2.828'0
970 m/s, Mach 2.828'0
970 m/s
Speed of Sound
Speed of Sound
Speed of Sound
Speed of Sound
Speed of Sound
-
-
-
-
-
Bulk Modulus
Bulk Modulus
Bulk Modulus
Bulk Modulus
Bulk Modulus
-
-
-
-
-
Shear Modulus
Shear Modulus
Shear Modulus
Shear Modulus
Shear Modulus
-
-
-
-
-
Young Modulus
Young Modulus
Young Modulus
Young Modulus
Young Modulus
Allotropes
Allotropes
Allotropes
Allotropes
Allotropes
 |
 |
 |
0.95 K, -272.20 °C
0.95 K, -272.20 °C
0.95 K, -272.20 °C
0.95 K, -272.20 °C
-272.20 °C
Melting Point
Melting Point
Melting Point
Melting Point
Melting Point
4.22 K, -268.93 °C
4.22 K, -268.93 °C
4.22 K, -268.93 °C
4.22 K, -268.93 °C
-268.93 °C
Boiling Point
Boiling Point
Boiling Point
Boiling Point
Boiling Point
-
-
-
-
-
Automatic Ignition
Automatic Ignition
Automatic Ignition
Automatic Ignition
Automatic Ignition
-
-
-
-
-
Flashpoint
Flashpoint
Flashpoint
Flashpoint
Flashpoint
5.19 K, -267.96 °C
5.19 K, -267.96 °C
5.19 K, -267.96 °C
5.19 K, -267.96 °C
-267.96 °C
Critical Temperature
Critical Temperature
Critical Temperature
Critical Temperature
Critical Temperature
227.00k Pa, 2 Atm
227.00k Pa, 2 Atm
227.00k Pa, 2 Atm
227.00k Pa, 2 Atm
2 Atm
Critical Pressure
Critical Pressure
Critical Pressure
Critical Pressure
Critical Pressure
0.151'300 W/(m K)
0.151'300 W/(m K)
0.151'300 W/(m K)
0.151'300 W/(m K)
0.151'300 W/(m K)
Thermal Conductivity
Thermal Conductivity
Thermal Conductivity
Thermal Conductivity
Thermal Conductivity
-
-
-
-
-
Thermal Expansion
Thermal Expansion
Thermal Expansion
Thermal Expansion
Thermal Expansion
5,193.10 J/(kg K)
5,193.10 J/(kg K)
5,193.10 J/(kg K)
5,193.10 J/(kg K)
5,193.10 J/(kg K)
Specific Heat
Specific Heat
Specific Heat
Specific Heat
Specific Heat
0.020 kJ/mol
0.020 kJ/mol
0.020 kJ/mol
0.020 kJ/mol
0.020 kJ/mol
Heat Fusion
Heat Fusion
Heat Fusion
Heat Fusion
Heat Fusion
0.083 kJ/mol
0.083 kJ/mol
0.083 kJ/mol
0.083 kJ/mol
0.083 kJ/mol
Heat Vaporisation
Heat Vaporisation
Heat Vaporisation
Heat Vaporisation
Heat Vaporisation
-
-
-
-
-
Heat Combustion
Heat Combustion
Heat Combustion
Heat Combustion
Heat Combustion
-
-
-
-
-
Curie Point
Curie Point
Curie Point
Curie Point
Curie Point
-
-
-
-
-
Neel Point
Neel Point
Neel Point
Neel Point
Neel Point
5/3
5/3
5/3
5/3
5/3
Adiabatic Index
Adiabatic Index
Adiabatic Index
Adiabatic Index
Adiabatic Index
Gas
Gas
Gas
Gas
Gas
Phase
Phase
Phase
Phase
Phase
-
-
-
-
-
Electrical Type
Electrical Type
Electrical Type
Electrical Type
Electrical Type
-
-
-
-
-
Conductivity
Conductivity
Conductivity
Conductivity
Conductivity
-
-
-
-
-
Resistivity
Resistivity
Resistivity
Resistivity
Resistivity
-
-
-
-
-
Superconducting Point
Superconducting Point
Superconducting Point
Superconducting Point
Superconducting Point
Diamagnetic
Diamagnetic
Diamagnetic
Diamagnetic
Diamagnetic
Magnetic Type
Magnetic Type
Magnetic Type
Magnetic Type
Magnetic Type
-0.000'000'005'9
-0.000'000'005'9
-0.000'000'005'9
-0.000'000'005'9
-0.000'000'005'9
Mass Susceptibility
Mass Susceptibility
Mass Susceptibility
Mass Susceptibility
Mass Susceptibility
-0.000'000'000'023'60
-0.000'000'000'023'60
-0.000'000'000'023'60
-0.000'000'000'023'60
-0.000'000'000'023'60
Molar Susceptibility
Molar Susceptibility
Molar Susceptibility
Molar Susceptibility
Molar Susceptibility
-0.000'000'001'05
-0.000'000'001'05
-0.000'000'001'05
-0.000'000'001'05
-0.000'000'001'05
Volume Susceptibility
Volume Susceptibility
Volume Susceptibility
Volume Susceptibility
Volume Susceptibility
Material Composition
Material Composition
Material Composition
Material Composition
Material Composition
23 %
23 %
23 %
23 %
23 %
Universe
Universe
Universe
Universe
Universe
-
-
-
-
-
Meteorites
Meteorites
Meteorites
Meteorites
Meteorites
23 %
23 %
23 %
23 %
23 %
Sun
Sun
Sun
Sun
Sun
0.000'005'23 %
0.000'005'23 %
0.000'005'23 %
0.000'005'23 %
0.000'005'23 %
Earth Crust
Earth Crust
Earth Crust
Earth Crust
Earth Crust
0.000'000'000'72 %
0.000'000'000'72 %
0.000'000'000'72 %
0.000'000'000'72 %
0.000'000'000'72 %
Oceans
Oceans
Oceans
Oceans
Oceans
-
-
-
-
-
Humans
Humans
Humans
Humans
Humans
4.002'601'9
4.002'601'9
4.002'601'9
4.002'601'9
4.002'601'9
Atomic Weight
Atomic Weight
Atomic Weight
Atomic Weight
Atomic Weight
31 pm
31 pm
31 pm
31 pm
31 pm
Atomic Radius
Atomic Radius
Atomic Radius
Atomic Radius
Atomic Radius
46 pm
46 pm
46 pm
46 pm
46 pm
Covalent Radius Single Bond
Covalent Radius Single Bond
Covalent Radius Single Bond
Covalent Radius Single Bond
Covalent Radius Single Bond
-
-
-
-
-
Covalent Radius Double Bond
Covalent Radius Double Bond
Covalent Radius Double Bond
Covalent Radius Double Bond
Covalent Radius Double Bond
-
-
-
-
-
Covalent Radius Triple Bond
Covalent Radius Triple Bond
Covalent Radius Triple Bond
Covalent Radius Triple Bond
Covalent Radius Triple Bond
140 pm
140 pm
140 pm
140 pm
140 pm
Van der Waals Radius
Van der Waals Radius
Van der Waals Radius
Van der Waals Radius
Van der Waals Radius
1s2
1s2
1s2
1s2
1s2
Electron Configuration
Electron Configuration
Electron Configuration
Electron Configuration
Electron Configuration
Hexagonal, Close Packed Single
Hexagonal, Close Packed Single
Hexagonal, Close Packed Single
Hexagonal, Close Packed Single
Hexagonal, Close Packed Single
Crystal Structure
Crystal Structure
Crystal Structure
Crystal Structure
Crystal Structure
-
-
-
-
-
Density as Solid
Density as Solid
Density as Solid
Density as Solid
Density as Solid
-
-
-
-
-
Density as Liquid
Density as Liquid
Density as Liquid
Density as Liquid
Density as Liquid
0.178'50 g/cm3
0.178'50 g/cm3
0.178'50 g/cm3
0.178'50 g/cm3
0.178'50 g/cm3
Density as Gas
Density as Gas
Density as Gas
Density as Gas
Density as Gas
Fm_3m
Fm_3m
Fm_3m
Fm_3m
Fm_3m
Space Group Name
Space Group Name
Space Group Name
Space Group Name
Space Group Name
225
225
225
225
225
Space Group Number
Space Group Number
Space Group Number
Space Group Number
Space Group Number
π/2, π/2 & π/2
π/2, π/2 & π/2
π/2, π/2 & π/2
π/2, π/2 & π/2
π/2, π/2 & π/2
Lattice Angles
Lattice Angles
Lattice Angles
Lattice Angles
Lattice Angles
424.2, 424.2 & 424.2 pm
424.2, 424.2 & 424.2 pm
424.2, 424.2 & 424.2 pm
424.2, 424.2 & 424.2 pm
424.2, 424.2 & 424.2 pm
Lattice Constants
Lattice Constants
Lattice Constants
Lattice Constants
Lattice Constants
0
0
0
0
0
Valence
Valence
Valence
Valence
Valence
-
-
-
-
-
Electronegativity
Electronegativity
Electronegativity
Electronegativity
Electronegativity
-48.24 kJ/mol
-48.24 kJ/mol
-48.24 kJ/mol
-48.24 kJ/mol
-48.24 kJ/mol
Electron Affinity
Electron Affinity
Electron Affinity
Electron Affinity
Electron Affinity
Ionisation Energy
Ionisation Energy
Ionisation Energy
Ionisation Energy
Ionisation Energy
 |
 |
Stable
Stable
Stable
Stable
Stable
Half Life
Half Life
Half Life
Half Life
Half Life
Stable
Stable
Stable
Stable
Stable
Lifetime
Lifetime
Lifetime
Lifetime
Lifetime
1s2 = 1, 0, 0, -1/2
1s2 = 1, 0, 0, -1/2
1s2 = 1, 0, 0, -1/2
1s2 = 1, 0, 0, -1/2
1s2 = 1, 0, 0, -1/2
Quantum Numbers
Quantum Numbers
Quantum Numbers
Quantum Numbers
Quantum Numbers
1.340'00 b σs
1.340'00 b σs
1.340'00 b σs
1.340'00 b σs
1.340'00 b σs
Neutron Cross Section
Neutron Cross Section
Neutron Cross Section
Neutron Cross Section
Neutron Cross Section
0.007'47 b σa
0.007'47 b σa
0.007'47 b σa
0.007'47 b σa
0.007'47 b σa
Neutron Mass Absorption
Neutron Mass Absorption
Neutron Mass Absorption
Neutron Mass Absorption
Neutron Mass Absorption
Stable Isotopes
Stable Isotopes
Stable Isotopes
Stable Isotopes
Stable Isotopes
 |
 |
Unstable Isotopes
Unstable Isotopes
Unstable Isotopes
Unstable Isotopes
Unstable Isotopes
 |
 |
 |
 |
 |
 |
 |
Isotopes Overview
Isotopes Overview
Isotopes Overview
Isotopes Overview
Isotopes Overview
| Isotope | Stability | Symbol | Type | Protons | Neutrons | Spin | Parity | Mass | Abundance | Mass Measure | Mass Excess | Binding Energy | Dipole Moment | Quadrupole Moment | Halflife in Years | Halflife in Seconds | A01 Decay Probability | A01 Decay Mode | A01 Decay Energy | A01 Decay Daughter | A01 Decay Link | A02 Decay Probability | A02 Decay Mode | A02 Decay Energy | A02 Decay Daughter | A02 Decay Link | A03 Decay Probability | A03 Decay Mode | A03 Decay Energy | A03 Decay Daughter | A03 Decay Link | A04 Decay Probability | A04 Decay Mode | A04 Decay Energy | A04 Decay Daughter | A04 Decay Link | A05 Decay Probability | A05 Decay Mode | A05 Decay Energy | A05 Decay Daughter | A05 Decay Link | A06 Decay Probability | A06 Decay Mode | A06 Decay Energy | A06 Decay Daughter | A06 Decay Link | Y01 Decay Product Yield | Y01 Decay Product Nuclide | Y02 Decay Product Yield | Y02 Decay Product Nuclide | Y03 Decay Product Yield | Y03 Decay Product Nuclide | Y04 Decay Product Yield | Y04 Decay Product Nuclide | Y05 Decay Product Yield | Y05 Decay Product Nuclide | Y06 Decay Product Yield | Y06 Decay Product Nuclide | Y07 Decay Product Yield | Y07 Decay Product Nuclide | Y08 Decay Product Yield | Y08 Decay Product Nuclide | Y09 Decay Product Yield | Y09 Decay Product Nuclide | Y10 Decay Product Yield | Y10 Decay Product Nuclide | Y11 Decay Product Yield | Y11 Decay Product Nuclide | Y12 Decay Product Yield | Y12 Decay Product Nuclide | ||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Isotope_002_he_2_u | Unstable | ²He | Boson | 2 | p | 0 | n | 0 | 1 | 2.015'894'000'0 | u | ~ 0 | % | ~ 0 | ? | MeV | ? | MeV | - | - | 3.17E-17 | year | 1.000 | nano-seconds ( x⁻⁹ ) | 99.990'000 | % | p | ? | keV | ¹H | ²He > [ 99.99 % , p , ? keV ] > ¹H | 0.010'000 | % | β+ | ? | keV | ²H | ²He > [ 0.01 % , β+ , ? keV ] > ²H | 99.990'000 | % | ¹H | 0.010'000 | % | ²H | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Isotope_002_he_3_s | Stable | ³He | Fermion | 2 | p | 1 | n | 1/2 | 1 | 3.016'029'319'1 | u | 0.000'137 | % | 0.000'004'132'0 | 14.931'214'750'0 | MeV | 2.572'681'000'0 | MeV | -2.127'624'850'0 | nm | - | - | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Isotope_002_he_4_s | Stable | ⁴He | Boson | 2 | p | 2 | n | 0 | 1 | 4.002'603'254'2 | u | 99.999'863 | % | 4.002'597'770'6 | 2.424'915'650'0 | MeV | 7.073'915'000'0 | MeV | - | - | - | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Isotope_002_he_5_u | Unstable | ⁵He | Fermion | 2 | p | 3 | n | 3/2 | -1 | 5.012'223'624'0 | u | ~ 0 | % | ~ 0 | 11.386'233'000'0 | MeV | 5.481'132'000'0 | MeV | - | - | 2.22E-29 | year | 700.000 | yocto-seconds ( x⁻²⁴ ) | 100.000'000 | % | n | 890.000 | keV | ⁴He | ⁵He > [ 100 % , n , 890.0 keV ] > ⁴He | 100.000'000 | % | ⁴He | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Isotope_002_he_6_u | Unstable | ⁶He | Boson | 2 | p | 4 | n | 0 | 1 | 6.018'889'124'0 | u | ~ 0 | % | ~ 0 | 17.595'106'000'0 | MeV | 4.878'017'000'0 | MeV | - | - | 2.56E-8 | year | 806.700 | milli-seconds ( x⁻³ ) | 100.000'000 | % | β- | 3,508.313 | keV | ⁶Li | ⁶He > [ 100 % , β- , 3,508.313 keV ] > ⁶Li | 0.000'280 | % | β-α | ? | keV | ⁴He | ⁶He > [ 0.00028 % , β-α , ? keV ] > ⁴He | 99.990'000 | % | ⁶Li | ⁴He | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Isotope_002_he_7_u | Unstable | ⁷He | Fermion | 2 | p | 5 | n | 3/2 | -1 | 7.028'020'618'0 | u | ~ 0 | % | ~ 0 | 26.101'038'000'0 | MeV | 4.119'070'000'0 | MeV | - | - | 9.19E-29 | year | 2.900 | zepto-seconds ( x⁻²¹ ) | 100.000'000 | % | n | 434.600 | keV | ⁶He | ⁷He > [ 100 % , n , 434.6 keV ] > ⁶He | 99.990'000 | % | ⁶Li | ⁶He | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Isotope_002_he_8_u | Unstable | ⁸He | Boson | 2 | p | 6 | n | 0 | 1 | 8.033'921'897'0 | u | ~ 0 | % | ~ 0 | 31.598'044'000'0 | MeV | 3.925'975'000'0 | MeV | - | - | 3.77E-9 | year | 119.000 | milli-seconds ( x⁻³ ) | 84.000'000 | % | β- | 9,671.000 | keV | ⁸Li | ⁸He > [ 84 % , β- , 9,671.0 keV ] > ⁸Li | 15.100'000 | % | β- n | 7,571.000 | keV | ⁷Li | ⁸He > [ 15.1 % , β- n , 7,571.0 keV ] > ⁷Li | 83.899'900 | % | ⁴He | ⁷Li | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Isotope_002_he_9_u | Unstable | ⁹He | Fermion | 2 | p | 7 | n | 1/2 | -1 | 9.043'950'286'0 | u | ~ 0 | % | ~ 0 | 40.939'429'000'0 | MeV | 3.348'637'000'0 | MeV | - | - | 2.22E-28 | year | 7.000 | zepto-seconds ( x⁻²¹ ) | 100.000'000 | % | n | 1,270.100 | keV | ⁸He | ⁹He > [ 100 % , n , 1,270.1 keV ] > ⁸He | 83.899'900 | % | ⁴He | ⁷Li | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Isotope_002_he_10_u | Unstable | ¹⁰He | Boson | 2 | p | 8 | n | 0 | 1 | 10.052'398'837'0 | u | ~ 0 | % | ~ 0 | 48.809'203'000'0 | MeV | 3.033'927'000'0 | MeV | - | - | 8.56E-29 | year | 2.700 | zepto-seconds ( x⁻²¹ ) | 100.000'000 | % | 2n | 1,068.500 | keV | ⁸He | ¹⁰He > [ 100 % , 2n , 1,068.5 keV ] > ⁸He | 83.899'900 | % | ⁴He | ⁷Li |
