Basic Information

Name: Thallium 
Symbol: Tl 
Atomic Number: 81 
Atomic Mass: 204.3833 amu 
Melting Point: 303.5 °C (576.65 K, 578.3 °F) 
Boiling Point: 1457.0 °C (1730.15 K, 2654.6 °F) 
Number of Protons/Electrons: 81 
Number of Neutrons: 123 
Classification: Other Metals 
Crystal Structure: Hexagonal 
Density @ 293 K: 11.85 g/cm3 
Color: bluish
Date of Discovery: 1861 
Discoverer: Sir William Crookes 
Name Origin: From the Greek word thallos (young shoot) 
Uses: rat and ant poisons, detecting infrared radiation 
Obtained From: crookesite, hutchinsonite, lorandite