Return to the Main CHEMystery Page.
Return to the Periodic Table of the Elements

Element 61 - Promethium (Pm) sound

After Prometheus; discovered 1947; the only rare earth that has never been found in nature. Produced in nuclear reactors, radioactive promethium in an "atomic battery" no bigger than a drawing pin powers guided-missile instruments, watches, and radios.

Properties

Atomic Number: 61
Atomic Weight: (145)
Electron Configuration (at ground state): 1s22s22p63s23p63d104s24p64d104f55s25p66s2
Oxidation States (Bold most stable): +3
Boiling Point (K): 3273
Melting Point (K): 1315
Density (at 300K -- g/cm3): 7.22
Atomic Volume (at 300K -- cm3/mol) 22.4
Mass Number (Bold naturally occurring) -- Half-Life -- Disintigration Type: 145 -- 18 years -- orbital electron capture
147 -- 2.62 years -- beta particle (electron) emission
Covalent Radius (Å): 1.63
First Ionization Potential (V): 5.55
Electronegativity (Pauling's): 1.13
Electrical Conductivity (at 293K for polycrystalline material -- 106 (ohms)-1 cm-1): 2
Thermal Conductivity (at 300K -- W m-1 K-1): 17.9
Crystal Structure: Hexagonal
Acid-Base Properties: Very basic