General | States | Energies | Oxidation & Electrons |Appearance & Characteristics
Reactions | Other Forms |Radius | Conductivity | Abundance
Encyclopedia Britannica articles


Name Thulium Symbol Tm
atomic number 69 Atomic weight 168.9342
Density @ 293 K 9.33 g/cm3 Atomic volume 18.1 cm3/mol
Group Rare Earth, Lanthanides discovered 1879


state (s, l, g) s
melting point 1818.2 K boiling point 2000 K
Heat of fusion 16.840 kJ/mol Heat of vaporization 191.0 kJ/mol
Back to the top


1st ionization energy 596.7 kJ/mole electronegativity 1.25
2nd ionization energy 1163 kJ/mole electron affinity 50 kJ/mole
3rd ionization energy 2544 kJ/mole Specific heat 0.16 J/gK
heat atomization 232 kJ/mole atoms

Oxidation & Electrons

Shells 2,8,18,31,8,2 electron configuration [Xe] 4f13 6s2
minimum oxidation number 0 maximum oxidation number 3
min. common oxidation no. 0 max. common oxidation no. 3
Back to the top

Appearance & Characteristics

structure hcp: hexagonal close pkd color silvery-white
uses alloys toxicity
hardness mohs characteristics soft


reaction with air vigorous, = Tm2O3 reaction with 6M HCl mild, = H2, TmCl3
reaction with 6M HCl mild, = H2, TmCl3 reaction with 15M HNO3 mild, = Tm(NO3)3
reaction with 6M NaOH
Back to the top

Other Forms

number of isotopes 1 hydride(s) TmH2 TmH3
oxide(s) Tm2O3 chloride(s) TmCl2 TmCl3


ionic radius (2- ion) pm ionic radius (1- ion) pm
atomic radius 176 pm ionic radius (1+ ion) pm
ionic radius (2+ ion) 117 pm ionic radius (3+ ion) 102 pm
Back to the top


thermal conductivity 16.9 J/m-sec-deg electrical conductivity 13.5 1/mohm-cm
polarizability 21.8 A^3


source Monazite(phosphate),bastnaesite rel. abund. solar system -1.423 log
abundance earth's crust -0.3 log cost, pure 4100 $/100g
cost, bulk $/100g
Back to the top

World Wide Web presentation of Chemicool Periodic Table is © Copyright 1996-99 by David D. Hsu. Some data were provided by and used with the permission of JCE Software and is owned and copyright by the Division of Chemical Education, Inc. Additional data were provided by Perkin-Elmer through Peter Lykos of IIT. The information may not be redistributed without the permission of David Hsu or JCE Software.