lanthanum

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

Description

Lanthanum is silvery white, malleable, ductile, and soft enough to be cut with a knife. It is one of the most reactive of the rare-earth metals. It oxidises rapidly when exposed to air. Cold water attacks lanthanum slowly, and hot water attacks it much more rapidly. The metal reacts directly with elemental carbon, nitrogen, boron, selenium, silicon, phosphorus, sulphur, and with halogens. It is a component of, misch metal (used for making lighter flints).

General information

Discoveror: Carl Gustaf Mosander
Date discovered: 1839
Discovered at: Sweden
Meaning of name: From the Greek word "lanthanein" meaning "to lie hidden"

Physical data

Standard state: solid at 298 K
Colour: silvery white
Density of solid at ambient temperature/kg m^-3: 6146
Molar volume/cm³: 22.39

Radii /pm

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

Valence shell orbital radius maxima (R_max)

orbital	s	p	d	f
radius	220.1	no data	115.0	no data

Electronegativities

Both values are quoted on the Pauling scale.

Pauling: 1.10
Allred Rochow: 1.08

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: 1193
boiling point: 3743

Enthalpies /kJ mol^-1

fusion: 8.5
vaporization: 401

single bond enthalpies:

La-F	La-Cl	La-Br	La-I	La-La
no data	no data	no data	no data	247

Ionization enthalpies /kJ mol^-1

Number	Enthalpy
1st	538.1
2nd	1067
3rd	1850
4th	4820

Isotopes

This section gives some data for naturally occurring isotopes.

Nominal mass	Accurate mass	% natural abundance
138La	137.907105 (6)	0.0902 (2)
139La	138.906347 (5)	99.9098 (2)

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