Periodic Table/Thulium
← ErYb →
69Tm168.9342 Da

Thulium

Lanthanide·Period 6·f-block

Soft grey metallic element that belongs to the lanthanoids. One natural isotope exists, Tm-169, and seventeen artificial isotopes have been produced. No known uses for the element. Discovered in 1879 by Per Theodor Cleve.

Gallery

Ultrapure (99.997%) Crystalline Thulium, 22.3 grams, 3 × 3 × 2 cm in size

Jurii, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons, source: https://images-of-elements.com/thulium.php

Bohr model of Thulium

Physical Propertiesmass · density · phase · crystal

Atomic Mass

168.9342Da

Density

9.3210g/cm³

Phase (STP)

Solid

Melting Point

1818.2K

Boiling Point

2223.2K

Molar Heat

0.1600J/(mol·K)

Crystal Structure

HEX

Lattice Constant

3.540Å

Atomic Radiiatomic · covalent · van der Waals

Atomic (Empirical)

175.00pm

Covalent

164.00pm

Van der Waals

227.00pm

Electronic Propertieselectronegativity · ionization · affinity

Electron Configuration

[Xe] 4f13 6s2

Electron Shells

2, 8, 18, 31, 8, 2

Electronegativity

1.25Pauling

Electron Affinity

1.0kJ/mol

1st Ionization Energy

6.2kJ/mol

Oxidation States

+2, +3

Orbital DiagramAufbau · Hund's rule · Pauli exclusion

↑↓
1s2
↑↓
2s2
↑↓
↑↓
↑↓
2p6
↑↓
3s2
↑↓
↑↓
↑↓
3p6
↑↓
↑↓
↑↓
↑↓
↑↓
3d10
↑↓
4s2
↑↓
↑↓
↑↓
4p6
↑↓
↑↓
↑↓
↑↓
↑↓
4d10
↑↓
5s2
↑↓
↑↓
↑↓
5p6
↑↓
↑↓
↑↓
↑↓
↑↓
↑↓
↑
4f13
↑↓
6s2

Full: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 4f13 6s2Short: [Xe] 4f13 6s2

Ionization Energies (69 known)

1st6.2 kJ/mol2nd12.1 kJ/mol3rd23.7 kJ/mol4th42.4 kJ/mol5th65.4 kJ/mol6th98.0 kJ/mol7th116.0 kJ/mol8th133.0 kJ/mol9th160.0 kJ/mol10th180.0 kJ/mol11th205.0 kJ/mol12th239.0 kJ/mol13th274.0 kJ/mol14th295.0 kJ/mol15th317.0 kJ/mol16th352.0 kJ/mol17th387.0 kJ/mol18th424.0 kJ/mol19th460.0 kJ/mol20th496.0 kJ/mol21th530.0 kJ/mol22th570.0 kJ/mol23th603.0 kJ/mol24th825.0 kJ/mol25th866.0 kJ/mol26th911.0 kJ/mol27th958.0 kJ/mol28th1004.0 kJ/mol29th1050.0 kJ/mol30th1110.0 kJ/mol31th1157.0 kJ/mol32th1207.0 kJ/mol33th1255.0 kJ/mol34th1442.0 kJ/mol35th1490.0 kJ/mol36th1542.0 kJ/mol37th1591.0 kJ/mol38th1706.0 kJ/mol39th1761.0 kJ/mol40th1889.0 kJ/mol41th1945.2 kJ/mol42th3298.0 kJ/mol43th3409.0 kJ/mol44th3528.0 kJ/mol45th3653.0 kJ/mol46th3775.0 kJ/mol47th3895.0 kJ/mol48th4075.0 kJ/mol49th4199.0 kJ/mol50th4335.0 kJ/mol51th4461.0 kJ/mol52th4812.0 kJ/mol53th4922.0 kJ/mol54th5044.0 kJ/mol55th5157.0 kJ/mol56th5527.0 kJ/mol57th5656.0 kJ/mol58th5901.0 kJ/mol59th6023.0 kJ/mol60th13347.0 kJ/mol61th13651.0 kJ/mol62th13988.0 kJ/mol63th14300.0 kJ/mol64th15663.0 kJ/mol65th16036.0 kJ/mol66th16510.0 kJ/mol67th16814.3 kJ/mol68th67965.3 kJ/mol69th69387.4 kJ/molSuccessive Ionization Energies

Emission Spectrumvisible range · characteristic spectral lines

409
419
436
Tm emission
380nm750nm
409.4 nm(100%)418.8 nm(50%)436.0 nm(30%)

Abundanceby mass

🌍Earth's Crust
520.0 ppb
🌊Ocean
1.5e-7 ppm
✨Universe
100.0 ppt
🧬Human Body—

Log scale · ppm = parts per million by mass

Biological Role

No biological role

No known biological role. Tm-170 used in portable X-ray devices.

Discovery

Discovered By

Per Theodor Cleve

Named By

—

Year

1879

Nuclear Data

Known Isotopes

39

Stable Isotopes

2

Stable Mass Numbers

169, 182

Natural isotopic abundance (IUPAC recommended values)

Isotopes of Tm39 known

NuclideZNMass (AMU)Half-lifeDecayJπAbundance
144Tm6975143.9762112.30 μsp, β⁺10+—
145Tm6976144.9703893.17 μsp (1%)11/2-—
146Tm6977145.966661155 msp (1%), β⁺, β⁺p1+—
169Tmstable69100168.934219Stablestable (1%)1/2+10000.0000%
180Tm69111179.959023Unknownβ⁻, β⁻n——
181Tm69112180.961954Unknownβ⁻, β⁻n1/2+—
182Tmstable69113181.966194Stableβ⁻, β⁻n——

Click any isotope for its full page with decay chain:

144Tm145Tm146Tm147Tm148Tm149Tm150Tm151Tm152Tm153Tm154Tm155Tm156Tm157Tm158Tm159Tm160Tm161Tm162Tm163Tm164Tm165Tm166Tm167Tm168Tm169Tm170Tm171Tm172Tm173Tm174Tm175Tm176Tm177Tm178Tm179Tm180Tm181Tm182Tm
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