Lanthanum

Chemical, physical and material properties and data of the chemical element Lanthanum.

Contents

General Information about Lanthanum

Regular nameLanthanumChemical symbolLaOther namesHistorical namesName meaning, originDiscovery (year)OccurencePosition in the PSEGroup membership

Atomar Properties of Lanthanum

Atomic number Z57 = number of protonsStandard Atomic Weight138.90547 (7)

Electron configuration of Lanthanum

1s	2s	2p	3s	3p	3d	4s	4p	4d	4f	5s	5p	5d	5f	6s	6p	6d	6f	7s	7p
2	2	6	2	6	10	2	6	10		2	6	1		2

Shorthand electron configuration of Lanthanum: [Xe] 5d¹ 6s² .

Ionization Energies of Lanthanum

The following table lists the ionization energies IE (ionization potentials); the IE is the energy required in electron volt (eV) per atom to separate a given electron from an Lanthanum atom.

IE1	IE2	IE3	IE4	IE5
5.5769	11.059	19.1774	49.95	61.6

Isotopic Data of Lanthanum

An overview of the nuclides as well as the isotopic data and properties are listed on the following page: Lanthanum isotopes.

Chemistry of Lanthanum

Oxidation states+ 3Electronegativity1.1 (Pauling original)
1.10 (Pauling)
1.09 (Allen)
0.92 (Sanderson)
1.08 (Allred-Rochow)
3.1 eV (Pearson)Electron affinity0.55(2) eV
53(2) kJ mol^-1

Standard Electrode Potential

E⁰ (V)	Symbol	N_ox	Name Ox. Name Red.	Ox. Red.	e^-
-2.9	La	+ III 0	Lanthanum hydroxide Lanthanum	La(OH)₃ ⇄ La (s) + 3 OH^-	+ 3 e^-
-2.379	La	+ III 0	Lanthanum(III) cation Lanthanum	La³⁺ ⇄ La (s)	+ 3 e^-

Material and Physical Properties

Melting point920 °CEnthalpy of fusion (molar)6.20 kJ mol^-1Boiling point3464 °CEnthalpy of vaporization399.6 kJ mol^-1Density6.162 g cm^-3

External Data, Identifiers

CAS registry number7439-91-0InChI =1S/LaInChIKeyFZLIPJUXYLNCLC-UHFFFAOYSA-NPubChem ID23926

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Last update: 2022-12-12

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