Symbol: Re
Atomic Number: 75
Atomic Weight: 186.207
Element Classification: Transition Metal
Discovered By: Walter Noddack, Ida Tacke, Otto Berg
Discovery Date: 1925 (Germany)
Name Origin: Latin: Rhenus, the Rhine River.

Density (g/cc): 21.02
Melting Point (K): 3453
Boiling Point (K): 5900
Appearance: Dense, silvery-white metal
Atomic Radius (pm): 137
Atomic Volume (cc/mol): 8.85
Covalent Radius (pm): 128
Ionic Radius: 53 (+7e) 72 (+4e)
Specific Heat (@20C J/g mol): 0.138
Fusion Heat (kJ/mol): 34
Evaporation Heat (kJ/mol): 704
Thermal Conductivity (@25C W/m K):
Debye Temperature (K): 416.00
Pauling Negativity Number: 1.9
First Ionizing Energy (kJ/mol): 759.1
Oxidation States: 5, 4, 3, 2, -1
Electronic Configuration: [Xe] 4f14 5d5 6s2
Lattice Structure: Hexagonal (HEX)
Lattice Constant (): 2.760
Lattice C/A Ratio: 1.615

Mineral Hardness [no units]: 7.0
Brinell Hardness [/MN m-2]: 1320
Vickers Hardness [/MN m-2]: 2450

Note: Rhenium, which has a hexagonal close packed crystal structure, is very sensitive to cold work and will form mechanical twins. It may be difficult to get completely deformation-free microstructures. Attack-polishing additions can be made to the final polishing abrasive slurry, or vibratory polishing may be employed.

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