praseodymium

• Description
• General information
• Physical data
• Radii
• Electronegativities
• Solid state structure
• Temperatures
• Enthalpies
• Ionization Enthalpies
• Isotopes
• Further information

Description

Praseodymium is soft, silvery, malleable, and ductile. It was prepared in relatively pure form in 1931. 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" away when exposed to air. The metal should be stored under an inert atmosphere or under mineral oil or petroleum. The rare-earth oxides, including Pr₂O₃, are among the most refractory substances known. It is a component of misch metal, used for lighter flints, and of the glass in welders' goggles.

General information

Discoveror: Carl F. Auer von Welsbach
Date discovered: 1885
Discovered at: Austria
Meaning of name: From the Greek words "prasios didymos" meaning "green twin"

Physical data

Standard state: solid at 298 K
Colour: silvery white, yellowish tinge
Density of solid at ambient temperature/kg m^-3: 6640
Molar volume/cm³: 20.80

Radii /pm

Atomic: 247
Covalent (single bond):
Pauling radius for the ion [Pr]^-: no data

Valence shell orbital radius maxima (R_max)

orbital	s	p	d	f
radius	224.7	no data	no data	36.1

Electronegativities

Both values are quoted on the Pauling scale.

Pauling: 1.13
Allred Rochow: 1.07

Crystal Structure

structure: hcp (hexagonal close-packed)

The following CrystalMaker image represents the solid state structure. For most elements, the most stable allotrope is illustrated. Try WebElements version 2 for interactive virtual reality and CHIME images.

Temperatures (/K)

melting point: 1208
boiling point: 3563

Enthalpies /kJ mol^-1

fusion: 9.0
vaporization: 332

single bond enthalpies:

Pr-F	Pr-Cl	Pr-Br	Pr-I	Pr-Pr
no data	no data	no data	338.5	no data

Ionization enthalpies /kJ mol^-1

Number	Enthalpy
1st	523
2nd	1018
3rd	2086
4th	3761
5th	5550

Isotopes

This section gives some data for naturally occurring isotopes.

Nominal mass	Accurate mass	% natural abundance
141Pr	140.907647 (4)	100

Further Information

• Additional information about WebElements 1.2.2
• This is a licensed copy (here is the full list) of WebElements 1.2.2 and contains a subset of the material contained within the main version of WebElements (version 2)
• For further information please try WebElements version 2
• Sheffield Chemdex: perhaps the largest internet chemistry directory
• Sheffield Chemputer: interactive chemistry calculators on the WWW