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Praseodymium

From Academic Kids

CeriumPraseodymiumNeodymium
Pr
Pa  
 
 
Image:Pr-TableImage.png
General
Name, Symbol, Number Praseodymium, Pr, 59
Chemical series Lanthanides
Group, Period, Block _ , 6, f
Density, Hardness 6640 kg/m3, no data
Appearance silvery white, yellowish tinge
Atomic properties
Atomic weight 140.90765(2) u
Atomic radius (calc.) 185 (247) pm
Covalent radius 165 pm
van der Waals radius no data
Electron configuration [Xe]6s24f3
e- 's per energy level 2, 8, 18, 21, 8, 2
Oxidation states (Oxide) 3 (mildly basic)
Crystal structure hexagonal
Physical properties
State of matter solid
Melting point 1204 K (1707.8 ?F)
Boiling point 3793 K (6368 ?F)
Molar volume 20.8 ×10-6 m3/mol
Heat of vaporization 296.8 kJ/mol
Heat of fusion 6.89 kJ/mol
Vapor pressure 1,333224E-06 Pa at 1070 K
Velocity of sound 2280 m/s at 293.15 K
Miscellaneous
Electronegativity 1.13 (Pauling scale)
Specific heat capacity 193 J/(kg*K)
Electrical conductivity 1.48 106/m ohm
Thermal conductivity 12.5 W/(m*K)
1st ionization potential 527 kJ/mol
2nd ionization potential 1020 kJ/mol
3rd ionization potential 2086 kJ/mol
4th ionization potential 3761 kJ/mol
Most stable isotopes
iso NA half-life DM DE MeV DP
141Pr 100% 141Pr is stable with 82 neutrons
142Pr {syn.} 19.12 h β- 2.162 MeV 142Nd
ε 0.745 MeV 142Ce
143Pr {syn.} 13.57 d β- 0.934 MeV 143Nd
SI units & STP are used except where noted.

For other meanings of the abbreviation Pr or PR, see Pr and PR.

Praseodymium is a chemical element in the periodic table that has the symbol Pr and atomic number 59.

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Contents

Notable characteristics

Praseodymium is a soft silvery metallic element, and belongs to the lanthanide group. It is somewhat more resistant to corrosion in air than europium, lanthanum, cerium, or neodymium, but it does develop a green oxide coating that spalls off when exposed to air, exposing more metal to oxidation. For this reason, praseodymium should be stored under a light mineral oil or sealed in plastic or glass.

Applications

Uses of praseodymium:

History

The name Praseodymium comes from the Greek prasios, meaning green, and didymos, or twin.

In 1841, Mosander extracted the rare earth didymium from lanthana. In 1874, Per Teodor Cleve concluded that didymium was in fact two elements, and in 1879, Lecoq de Boisbaudran isolated a new earth, Samarium, from didymium obtained from the mineral samarskite. In 1885, the Austrian chemist baron C. F. Auer von Welsbach separated didymium into two elements, Praseodymium and Neodymium, which gave salts of different colors.

Occurrence

Praseodymium is found in the rare earth minerals monazite and bastnasite, and can be recovered from bastnasite or monazite by an ion exchange process. Praseodymium also makes up about 5% of Misch metal.

Compounds

Praseodymium compounds include:

Isotopes

Naturally occurring praseodymium is composed of one stable isotope, 141-Pr. 38 radioisotopes have been characterized with the most stable being 143-Pr with a half-life of 13.57 days and 142-Pr with a half-life of 19.12 hours. All of the remaining radioactive isotopes have half-lifes that are less than 5.985 hours and the majority of these have half lifes that are less than 33 seconds. This element also has 6 meta states with the most stable being 138m-Pr (t? 2.12 hours), 142m-Pr (t? 14.6 minutes) and 134m-Pr (t? 11 minutes).

The isotopes of praseodymium range in atomic weight from 120.955 u (121-Pr) to 158.955 u (159-Pr). The primary decay mode before the stable isotope, 141-Pr, is electron capture and the primary mode after is beta minus decay. The primary decay products before 141-Pr are element 58 (Cerium) isotopes and the primary products after are element 60 (Neodymium) isotopes.

Precautions

Like all rare earths, praseodymium is of low to moderate toxicity. Praseodymium has no known biological role.

References

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