Periodic table / Lanthanoids
59Praseodymium
Praseodymium is a lanthanoid in period 6, in the lanthanoid series. At 25 °C it is a solid.
- Symbol
- Pr
- Atomic number
- 59 protons in the nucleus
- Standard atomic weight
- 140.91 ± 0.01
- Electron configuration
- [Xe] 4f3 6s2
- Electrons in each shell
- 2, 8, 18, 21, 8, 2
- Group, period, block
- –, 6, f
- Family
- Lanthanoids
- State at 25 °C
- solid
- Electronegativity
- 1.13 (Pauling scale)
- First ionisation energy
- 527.8 kJ/mol (5.4702 eV) (estimated by NIST)
Where these numbers come from
Atomic weight: IUPAC CIAAW, abridged standard atomic weights 2024. Electron configuration and ionisation energy: NIST Atomic Spectra Database. Family, state and electronegativity: PubChem. See Sources. Melting points, boiling points and densities are left out for now: published values differ between sources, and we will add them once each has been checked.