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

Carbon has a valency of four. It is capable of forming single bonds with four other carbon atoms or atoms of some other monovalent element, etc. What is this property of carbon known as?