Thallium is the chemical element in the periodic table that has the symbol Tl and atomic number 81. This soft gray malleable poor metal resembles tin but discolors when exposed to air. Thallium is highly toxic and is used in rodent and insect poisons but since it can also cause cancer, this use has been cut back or eliminated in many countries. It is also used in infrared detectors.

GoldBamboo

81 mercury ← thallium → lead In ↑ Tl ↓ Uut periodic table ...
Wikipedia - [full article]

Resources

  • Thallium (Centers for Disease Control and Prevention)