Facts about the Classification of the Element Thallium
Thallium is classified in the 'Other Metals' section which can be located in groups 13, 14, and 15 of the Periodic Table. All of these elements are solid, have a relatively high density and are opaque.

Brief Facts about the Discovery and History of the Element Thallium
Thallium was discovered by Sir William Crookes in England in 1861. Claude-Auguste Lamy and Sir William Crookes isolated the metal independent of each other in 1862.

Occurrence of the element Thallium
Obtained from crookesite, hutchinsonite & lorandite

Common Uses of Thallium
Photocells
Rat poison
Ant killer
Thallium bromide-iodide crystals have been used as infrared optical materials
Gamma radiation detection equipment
Medical applications for the treatment of skin infections

The Properties of the Element Thallium

Name of Element : Thallium
Symbol of Element : Tl
Atomic Number of Thallium : 81
Atomic Mass: 204.3833 amu
Melting Point: 303.5 °C - 576.65 °K
Boiling Point: 1457.0 °C - 1730.15 °K
Number of Protons/Electrons in Thallium : 81
Number of Neutrons in Thallium : 123
Crystal Structure: Hexagonal
Density @ 293 K: 11.85 g/cm3
Color of Thallium : bluish-gray