Thulium

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

Contents

General Information about Thulium

Regular nameThuliumChemical symbolTmOther namesHistorical namesName meaning, originDiscovery (year)OccurencePosition in the PSEGroup membership

Atomar Properties of Thulium

Atomic number Z69 = number of protonsStandard Atomic Weight168.934218 (6)

Electron configuration of Thulium

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	13	2	6			2

Shorthand electron configuration of Thulium: [Xe] 4f¹³ 6s² .

Ionization Energies of Thulium

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 Thulium atom.

IE1	IE2	IE3	IE4
6.18431	12.05	23.68	42.7

Isotopic Data of Thulium

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

Chemistry of Thulium

Oxidation states+3Electronegativity1.1 (Pauling original)
1.25 (Pauling)Electron affinity1.029(22) eV
99(3) kJ mol^-1

Standard Electrode Potential

E⁰ (V)	Symbol	N_ox	Name Ox. Name Red.	Ox. Red.	e^-
-2.4	Tm	+ II 0	Thulium(II) cation Thulium	Tm²⁺ ⇄ Tm	+ 2 e^-
-2.319	Tm	+ III 0	Thulium(III) cation Thulium	Tm³⁺ ⇄ Tm	+ 3 e^-
-2.2	Tm	+ III + II	Thulium(III) cation Thulium(II) cation	Tm³⁺ ⇄ Tm²⁺	+ e^-

Material and Physical Properties

Melting point1545 °CEnthalpy of fusion (molar)16.84 kJ mol^-1Boiling point1950 °CEnthalpy of vaporization247 kJ mol^-1Density9.318 g cm^-3 (25 °C)

External Data, Identifiers

CAS registry number7440-30-4InChI =1S/TmInChIKeyFRNOGLGSGLTDKL-UHFFFAOYSA-NPubChem ID23961

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isotopes

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Last update: 2022-12-12

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