Symbol: Rb
Atomic Number: 37
Atomic Weight: 85.4678
Element Classification: Alkali Metal
Discovered By: R. Bunsen, G. Kirchoff
Discovery Date: 1861 (Germany)
Name Origin: Latin: rubidus (deep red); the color its salts impart to flames.

Density (g/cc): 1.532
Melting Point (K): 312.2
Boiling Point (K): 961
Appearance: Soft, silvery-white, highly reactive metal
Atomic Radius (pm): 248
Atomic Volume (cc/mol): 55.9
Covalent Radius (pm): 216
Ionic Radius: 147 (+1e)
Specific Heat (@20C J/g mol): 0.360
Fusion Heat (kJ/mol): 2.20
Evaporation Heat (kJ/mol): 75.8
Thermal Conductivity (@25C W/m K):
Debye Temperature (K): n/a
Pauling Negativity Number: 0.82
First Ionizing Energy (kJ/mol): 402.8
Oxidation States: 1
Electronic Configuration: [Kr] 5s1
Lattice Structure: Body-Centered Cubic (BCC)
Lattice Constant (): 5.590
Lattice C/A Ratio: n/a

Mineral Hardness [no units]: 0.3
Brinell Hardness [/MN m-2]: 0.216

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