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Helium


1
2
4.002602
KEY
Chemical Element Symbol Key

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Helium
Columbia Encyclopedia
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Lithium (Li)
Symbol: He
Atomic Number: 2
Atomic Weight: 4.002602
Element Classification: Inert Gas
Discovered By: Sir William Ramsey, Nils Langet, P.T.Cleve
Discovery Date: 1895 (Scotland/Sweden)
Name Origin: Greek: helios (sun).
Density (g/cc): 0.147 (@ -270�C)
Melting Point (K): 0.95
Boiling Point (K): 4.216
Appearance: Inert, colorless, odorless, tasteless gas
Atomic Radius (pm): 0.0
Atomic Volume (cc/mol): 31.8
Covalent Radius (pm): n/a
Ionic Radius: 93
Specific Heat (@20°C J/g mol): 5.188
Fusion Heat (kJ/mol): n/a
Evaporation Heat (kJ/mol): 0.08
Thermal Conductivity (@25°C W/m K):
Debye Temperature (K): n/a
Pauling Negativity Number: n/a
First Ionizing Energy (kJ/mol): 2361.3
Oxidation States: n/a
Electronic Configuration: 1s2
Lattice Structure: Hexagonal (HEX
Lattice Constant (Å): 3.570
Lattice C/A Ratio: 1.633


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