Chemical Elements.com - Thulium (Tm)

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Basic Information

Name: Thulium
Symbol: Tm
Atomic Number: 69
Atomic Mass: 168.9342 amu
Melting Point: 1545.0 °C (1818.15 K, 2813.0 °F)
Boiling Point: 1727.0 °C (2000.15 K, 3140.6 °F)
Number of Protons/Electrons: 69
Number of Neutrons: 100
Classification: Rare Earth
Crystal Structure: Hexagonal
Density @ 293 K: 9.321 g/cm³
Color: silverish

Atomic Structure

Number of Energy Levels: 6

First Energy Level:

Second Energy Level:

Third Energy Level:

Fourth Energy Level:

Fifth Energy Level:

Sixth Energy Level:

Isotopes

Isotope	Half Life
Tm-168	93.1 days
Tm-169	Stable
Tm-170	128.6 days
Tm-171	1.92 years
Tm-172	2.65 days

Facts

Date of Discovery: 1879
Discoverer: Per Theodor Cleve
Name Origin: From Thule (ancient name of Scandinavia)
Uses: power for portable x-ray machines
Obtained From: gadolinite, euxenite, xenotime

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