Thulium at Chemical Elements.com 


 

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

[Bohr Model of Thulium]  
Number of Energy Levels: 6

    First Energy Level: 2
    Second Energy Level: 8
    Third Energy Level: 18
    Fourth Energy Level: 31
    Fifth Energy Level: 8
    Sixth Energy Level: 2

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