Symbol: Pr
Atomic Number: 59
Atomic Weight: 140.90765
Element Classification: Rare Earth Element (Lanthanide Series)
Discovered By: C.F. Aver von Welsbach
Discovery Date: 1885 (Austria)
Name Origin: Greek: prasios and didymos (green twin); from its green salts.

Density (g/cc): 6.773
Melting Point (K): 1204
Boiling Point (K): 3785
Appearance: Silvery white, moderately soft, malleable, and ductile metal
Atomic Radius (pm): 182
Atomic Volume (cc/mol): 20.8
Covalent Radius (pm): 165
Ionic Radius: 90 (+4e) 101.3 (+3e)
Specific Heat (@20C J/g mol): 0.192
Fusion Heat (kJ/mol): 11.3
Evaporation Heat (kJ/mol): 331
Thermal Conductivity (@25C W/m K):
Debye Temperature (K): n/a
Pauling Negativity Number: 1.13
First Ionizing Energy (kJ/mol): 526.6
Oxidation States: 4, 3
Electronic Configuration: [Xe] 4f3 6s2
Lattice Structure: Hexagonal (HEX)
Lattice Constant (): 3.670
Lattice C/A Ratio: 1.614

Brinell Hardness [/MN m-2]: 481
Vickers Hardness [/MN m-2]: 400

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