Promethium (Pm), element 61 – Learn Acer periodic table

Promethium

Lanthanide, atomic number 61.

Promethium, originally prometheum, is a chemical element with the symbol Pm and atomic number 61. All of its isotopes are radioactive; it is one of only two such elements that are followed in the periodic table by elements with stable forms, a distinction shared with technetium. Chemically, promethium is a lanthanide, which forms salts when combined with other elements.

Facts

Symbol Pm. Atomic mass 145.0 u. Group 3, period 6. Electron configuration [Xe] 4f5 6s2. Electrons per shell 2, 8, 18, 23, 8, 2. State at room temperature: Solid. Melting point 1041.8 °C, boiling point 2999.8 °C. Discovered by Chien Shiung Wu.

Element data from Wikipedia, CC BY-SA 3.0.