Symbol Tm
Atomic Number 69
Atomic Mass 168.93 g.mol -1
Discovered by Per Theodor Cleve in 1879

Chemical Properties of Thulium

Group Lanthanides Melting point 1545°C, 2813°F, 1818 K
Period 6 Boiling point 1950°C, 3542°F, 2223 K
Block f Density (g cm−3) 9.32
Atomic number 69 Relative atomic mass 168.934
State at 20°C Solid Key isotopes 169Tm
Electron configuration [Xe] 4f136s2 CAS number 7440-30-4
ChemSpider ID 22400 ChemSpider is a free chemical structure database

What is Thulium?

  • Thulium is a chemical element having an atomic number 69 with the symbol Tm, discovered by Theodor Cleve in the year 1879.
  • It is the thirteenth element in the lanthanide series in the periodic table.
  • The element is barely traced purely in nature but it is traced in minute amounts in minerals with other rare earth metals.

Uses of Thulium

  • It is used for laser manufacturing and for surgical purposes.
  • Thulium is used as a source of radiation from portable X-ray devices and in nuclear reactions.
  • Despite being slightly expensive, superconductors of high temperature use thulium.
  • It is used for manufacturing ferrites, ceramic magnetic materials for microwave items.

Properties of Thulium

  • The element is the second least abundant element in the lanthanide series.
  • It would tarnish once exposed to air due to its malleability and ductility.
  • The element contains one natural isotope, 169Tm which has a half-life of 1.92 years.
  • The remaining isotopes of the element have a half-life that ranges from 2 minutes to 64 hours.

Certain Facts About Thulium

  • Natural thulium in ceramic magnetic materials is used in microwave equipment and are useful for doping fiber lasers.
  • Once used for bombarding in a nuclear reactor, thulium could be employed as a radiation source in portable X-ray equipment.
  • Unlike the other lanthanides, thulium has a low-to-moderate acute toxic rating.

Practise This Question

The wave function, Ψn,l,ml is a mathematical function whose value depends upon spherical polar coordinates (r, θ, Ф) of the electron and characterized by the quantum numbers n, l and m. Here r is distance from nucleus, θ is colatitude and Ф is azimuth. In the mathematical functions given in the Table, Z is atomic number and a0 is Bohr radius.

Column 1 Column 2 Column 3
(i) 1s orbital (i) Ψn,l,ml(Za0)32e(Zra0) (P)
(ii) 2s orbital (ii) One radial node (Q) Probability density at nucleus 1a30
(iii) 2 pz orbital (iii) Ψn,l,ml(Za0)52re(Zr2a0)cosθ (R) Probability density is maximum at nucleus
(iv) 3d2z orbital (iv) xy-plane is a nodal plane (S) Energy needed to excite electron from n = 2 state to n = 4 state is2732 times the energy needed to excite electron from n = 2 state to n = 6 state

For the given orbital in Column 1, the only CORRECT combination for any hydrogen-like species is