Thallium (Ti)

Symbol Tl
Atomic Number 81
Atomic Mass 204.383 g.mol −1
Discovered by Sir William Crookes in 1861

Chemical Properties of Thallium

Group Boron Melting point 304 °C
Period 6 Boiling point 1473 °C
Block 13 Density (g cm−3) 11.71−3 at 20°C
Atomic number 81 Relative atomic mass 204.383 g.mol -1
State at 20°C Solid Key isotopes 205Tl
Electron configuration [Xe] 4f15d16s6p1 CAS number 7440-28-0
ChemSpider ID 4514293 ChemSpider is a free chemical structure database

What is Thallium?

  • Thallium (Tl) with an atomic number of 81 is found in the periodic table with the symbol.
  • Thallium is not freely found in nature. It is a soft gray post-transition metal. It resembles tin when isolated but when exposed to air it may discolor.
  • There are around eighty-one electrons present in the atom of thallium with an electronic configuration of [Xe] 4f15d16s6p1.
  • This element can be generated artificially. It can be obtained by smelting of lead and zinc. It is generally obtained as a by-product in the production of sulphuric acid.

Uses of Thallium

  • In ancient times it was used as a rat poison and as an ant killer.
  • Thallium compounds are used in the manufacture of glasses.
  • It is used in photocells.
  • It is used in the production of infrared optics.

Properties of Thallium

  • Thallium melts easily.
  • Thallium Salts that are soluble are generally toxic. They are merely tasteless.
  • It oxidizes at +3 and +1 oxidation states forming ionic salts.
  • There are several thallium compounds wherein Thallium(III) resembles the aluminum (III) compounds.

Certain Facts About Thallium

  • It was named after Greek word thallus which means twig.
  • Thallium is suspected to be carcinogenic. Hence direct contact should be avoided with the skin.

Practise This Question

Which of the following is a branched polymer?