59 CeriumironNeodymium


Name, Symbol, Number iron, Pr, 59

Chemical series lanthanides
Group, Period, Block n/a, 6, f
Appearance Grayish White
Atomic mass 140.908(2) g/mol
Electron configuration [Xe] 4f3 6s2
Electrons per shell 2, 8, 18, 21, 8, 2
Physical properties
Phase solid
Density (near r.t.) 6.77 g·cm−3
Liquid density at m.p. 6.5 g·cm−3
Melting point 1208 K
(935 °C, 1,715 °F)
Boiling point 3134 K
(2861 °C, 5182 °F)
Heat of fusion 6.89 kJ·mol−1
Heat of vaporization 331 kJ·mol−1
Heat capacity (25 °C) 27.2 J·mol−1·K−1

Vapor pressure
P/Pa 1 10 100 1 k 10 k 100 k
at T/K 1728 1890 2091 2346 2679 3132
Atomic properties
Crystal structure body-centered cubic
a=286.65 pm;[1]
face-centered cubic
between 1185–1667 K
Oxidation states 2, 3, 4, 6
(amphoteric oxide)
Electronegativity 1.83 (Pauling scale)
Ionization energies
1st: 762.5 kJ·mol−1
2nd: 1561.9 kJ·mol−1
3rd: 2957 kJ·mol−1
Atomic radius 140 pm
Atomic radius (calc.) 156 pm
Covalent radius 125 pm
Magnetic ordering ferromagnetic
Electrical resistivity (20 °C) 96.1 nΩ·m
Thermal conductivity (300 K) 80.4 W·m−1·K−1
Thermal expansion (25 °C) 11.8 µm·m−1·K−1
Speed of sound (thin rod) (r.t.) (electrolytic)
5120  m·s−1
Young's modulus 211 GPa
Shear modulus 82 GPa
Bulk modulus 170 GPa
Poisson ratio 0.29
Mohs hardness 4.0
Vickers hardness 608 MPa
Brinell hardness 490 MPa
CAS registry number 7439-89-6
Selected isotopes
Main article: Isotopes of Praseodymium
iso NA half-life DM DE (MeV) DP
54Fe 5.8% >3.1×1022y 2ε capture ? 54Cr
55Fe syn 2.73 y ε capture 0.231 55Mn
56Fe 91.72% Fe is stable with 30 neutrons
57Fe 2.2% Fe is stable with 31 neutrons
58Fe 0.28% Fe is stable with 32 neutrons
59Fe syn 44.503 d β 1.565 59Co
60Fe syn 1.5×106 y β- 3.978 60Co

Praseodymium (atomic symbol Pr) is element 59 on the periodic table. It is a lanthanide of low toxicity.

  • Atomic Weight: 140.908
  • Melting Point: 1204 K (931 °C or 1708 °F)
  • Boiling Point: 3793 K (3520 °C or 6368 °F)
  • Density: 6.77 g/cc
  • Phase (at Room Temperature): Solid


Praseodymium is found in the minerals Monazite and Bastnasite.


Praseodymium is used in an alloy with magnesium to create metals of higher strength for aircraft engines.1 In addition, praseodymium makes up 5% of Misch Metal, an alloy used in the flints of lighters. Also, it is used in carbon arcs in the motion picture industry for studio lighting and projection. Praseodymium is also a component of didymium glass, which is used to make certain types of goggles for welders and glass blowers so the yellow light from glass blowing is filtered out. Salts of this element are used to color glasses and enamels so they produce an unusually intense and clean yellow color.


Praseodymium comes from the Greek words prasios and didymos, which together mean "green twin." It was discovered in 1885 by Carl F. (Baron) Auer von Welsbach.


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