#59 / 118
59Pr140.91
Lanthanides (Rare Earths)solid at STPF-block

Praseodymium

Group: f-blockPeriod: 6Standard Atomic Weight: 140.91 u

Why is Praseodymium in this position?

Understanding the scientific rationale behind Praseodymium's position in the periodic table:

Group Assignment
Group Lanthanide / Actinide

Lanthanide series element filling the 4f subshell.

Period Assignment
Period 6

Belongs to Period 6 because its outermost electrons occupy n=6.

Orbital Block
F-block

Belongs to the f-block because the differentiating electrons enter the 4f subshell (4f³ 6s²).

Chemical Category
Lanthanides (Rare Earths)

Classified as a lanthanide rare earth metal.

Atomic Structure & Bohr Shell Model

Shell Distribution: [2, 8, 18, 21, 8, 2]

Bohr Atomic Shell Model(2, 8, 18, 21, 8, 2)

Hover or tap any shell orbit ring to inspect electron counts and 2n² capacities.

59 Protons (p⁺)82 Neutrons (n⁰)
KShell K: Electron 1 of 2Shell K: Electron 2 of 2LShell L: Electron 1 of 8Shell L: Electron 2 of 8Shell L: Electron 3 of 8Shell L: Electron 4 of 8Shell L: Electron 5 of 8Shell L: Electron 6 of 8Shell L: Electron 7 of 8Shell L: Electron 8 of 8MShell M: Electron 1 of 18Shell M: Electron 2 of 18Shell M: Electron 3 of 18Shell M: Electron 4 of 18Shell M: Electron 5 of 18Shell M: Electron 6 of 18Shell M: Electron 7 of 18Shell M: Electron 8 of 18Shell M: Electron 9 of 18Shell M: Electron 10 of 18Shell M: Electron 11 of 18Shell M: Electron 12 of 18Shell M: Electron 13 of 18Shell M: Electron 14 of 18Shell M: Electron 15 of 18Shell M: Electron 16 of 18Shell M: Electron 17 of 18Shell M: Electron 18 of 18NShell N: Electron 1 of 21Shell N: Electron 2 of 21Shell N: Electron 3 of 21Shell N: Electron 4 of 21Shell N: Electron 5 of 21Shell N: Electron 6 of 21Shell N: Electron 7 of 21Shell N: Electron 8 of 21Shell N: Electron 9 of 21Shell N: Electron 10 of 21Shell N: Electron 11 of 21Shell N: Electron 12 of 21Shell N: Electron 13 of 21Shell N: Electron 14 of 21Shell N: Electron 15 of 21Shell N: Electron 16 of 21Shell N: Electron 17 of 21Shell N: Electron 18 of 21Shell N: Electron 19 of 21Shell N: Electron 20 of 21Shell N: Electron 21 of 21OShell O: Electron 1 of 8Shell O: Electron 2 of 8Shell O: Electron 3 of 8Shell O: Electron 4 of 8Shell O: Electron 5 of 8Shell O: Electron 6 of 8Shell O: Electron 7 of 8Shell O: Electron 8 of 8PShell P: Electron 1 of 2Shell P: Electron 2 of 2PrZ = 59

Educational Note: This Niels Bohr planetary model visually illustrates principal quantum energy shells ($n=1, 2, 3\dots$) and electron counts. In modern quantum mechanics (Schrödinger model), electrons do not orbit in fixed circular planetary tracks, but exist as 3D probability clouds (orbitals: $s, p, d, f$) governed by the Heisenberg uncertainty principle.

Electron Shell Filling Breakdown

Shell K (n=1):2 / 2 electrons (100%)
Shell L (n=2):8 / 8 electrons (100%)
Shell M (n=3):18 / 18 electrons (100%)
Shell N (n=4):21 / 32 electrons (66%)
Shell O (n=5):8 / 50 electrons (16%)
Shell P (n=6):2 / 72 electrons (3%)
Aufbau Electron Configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f³ 5s² 5p⁶ 6s²

Neutral ground state configuration. Valence electrons: 5.

Atomic & Quantum Properties

Electronegativity (Pauling)1.13 Pauling
1st Ionization Energy527 kJ/mol
Electron Affinity-50 kJ/mol
Atomic Radius (empirical)185 pm
Common Oxidation States+3
Crystal StructureDouble HCP

Physical & Thermal Properties

Density at STP6.77 g/cm³
Melting Point931 °C (1204 K)
Boiling Point3520 °C (3793 K)
Magnetic OrderingParamagnetic
Discovery Year1885
Discovered ByCarl Auer von Welsbach

Real-World Uses, Occurrence & Compounds

Major Industrial & Everyday Uses
  • Praseodymium-doped neodymium permanent magnets (PrNd) for EV traction motors and wind turbines
  • Didymium glass safety goggles absorbing yellow sodium flare in glassblowing and arc welding
  • Bright canary-yellow ceramic pigments (Praseodymium zircon yellow)
  • Aircraft jet engine high-strength magnesium alloy components
Occurrence in Nature

Found in monazite and bastnäsite minerals, separated from twin element neodymium via liquid-liquid solvent extraction.

Etymology & Name Origin

From Greek 'prasios' meaning leek-green and 'didymos' meaning twin

Important Chemical Compounds
Pr₆O₁₁ (Praseodymium oxide)
PrCl₃ (Praseodymium chloride)
Pr(NO₃)₃ (Praseodymium nitrate)
Interesting Chemical Facts
  • For decades, chemists believed 'didymium' was a single element until Carl Auer von Welsbach split it into praseodymium and neodymium in 1885.
  • Didymium safety glass containing praseodymium and neodymium filters out the blinding 589 nm yellow glare of hot sodium in glassblowing.
  • In 2000, scientists used a praseodymium-doped crystal to slow a pulse of light down to just a few hundred meters per second.
Safety & Handling Note

Low to moderate toxicity; metal filings tarnish readily in air and can spark upon friction.