Question: is thallium a transition metal?
Answer: Thallium is a chemical element with the symbol Tl and atomic number 81. It is a gray post-transition metal that is not found free in nature. When isolated, thallium resembles tin, but discolors when exposed to air. ... The +3 state resembles that of the other elements in group 13 (boron, aluminium, gallium, indium).