Helium
Content created by REAL intelligence since 2016
Naming and classification
Physical properties
Reactions
Thermodynamic properties
Crystal structure
Atom properties
Electrochemical properties
Biological properties
Occurrence, isolation & synthesis
Isotopes
Safety
Uses
History
References
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Physical state @ 20°C: |
Gas [2] |
|
Color: |
Colorless [2] |
|
Luminescence: |
- |
|
Luster: |
- |
|
Transparancy: |
- |
|
Streak: |
- |
|
Odor: |
Almost odorless [2] |
|
Molecular weight (g/mol): |
4.002602(2) [11] |
|
Melting point (°C):  |
-272 [2] |
|
Boiling point (°C): |
-268.93 [1] |
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Density (g/cm3): |
Gas, 3He: 0.0001347 [4]
Gas, 4He: 0.00017850 [4]
Liquid, 3He: 0.589 [4]
Liquid, 4He: 0.1250 [4]
Critical, 3He: 0.000413 [4]
Critical, 4He: 0.0006964 [4] |
|
Relative vapor density (g/cm3): |
- |
|
Molar volume (cm3): |
57 (Critical) [3] |
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Vapor pressure: |
- |
|
Critical temperature (°C): |
3He: -269.826 [4]
4He: -267.9486 [4] |
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Critical pressure (kPa): |
3He: 116.4 [4]
4He: 227.5 [4] |
|
Elastic properties:
Young's modulus (GPa):
Rigidity modulus (GPa):
Bulk modulus (GPa):
Poisson ratio: |
-
-
-
- |
|
Hardness:
Mineral hardness:
Brinell hardness (MN/m2):
Vicker hardness (MN/m2): |
-
-
- |
|
Reflectivity (%): |
- |
|
Refractive index: |
1.000035 (g)
1.028 (l) |
|
Velocity of sound (m/s): |
- |
|
Surface tension: |
- |
|
Solubility: |
Water: 8.6 g/l (20 °C) [2]
Organic solvents: Insoluble (20 °C) [2] |
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Decomposition temperature: |
n/a |
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Flammability: |
n/a |
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Flash point: |
n/a |
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Auto ignition temperature: |
n/a |
|
flammability or explosive limits (% v/v):
Upper:
Lower: |
n/a
n/a |
|
