61 - Promethium lanthanide
Discovered by Chien Shiung Wu in 1945
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.
Periodic table
| Shell | Electrons | Orbitals |
|---|---|---|
| 1 | 2 | 2 in 1s |
| 2 | 8 | 2 in 2s + 6 in 2p |
| 3 | 18 | 2 in 3s + 6 in 3p + 10 in 3d |
| 4 | 23 | 2 in 4s + 6 in 4p + 10 in 4d + 5 in 4f |
| 5 | 8 | 2 in 5s + 6 in 5p |
| 6 | 2 | 2 in 6s |
Electron shells
metallic Appearance
145 u Atomic Mass
1.85 Å Atomic Radius
3.27k K Boiling Point
7 Group
3 Common Oxidation States
1.99 Å Covalent Radius
7.26 g/cm³ Density
12.4 kJ/mol Electron Affinity
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f5 Electron Configuration
[Xe] 4f5 6s2 Electron Configuration (semantic)
1.13 Electronegativity
61 Electrons
5.58 eV First Ionization Energy
540, 1050, 2150, 3970 kJ/mol Ionization Energies
1.2k K Melting Point
29 Mendeleev Number
6 Number of Shells
84 Neutrons
61 Atomic Number
14 Number of Isotopes
3 Oxidation States
6 Period
Solid Phase
61 Protons
2, 8, 18, 23, 8, 2 Electron Shell Occupations