Name: terbium
Symbol: Tb
Atomic number: 65
Atomic weight: 158.92534 (2)
Group in periodic table:
Group name: Lanthanoid
Period in periodic table: 6 (lanthanoid)
Block in periodic table: f-block
CAS registry ID: 7440-27-9
Terbium is reasonably stable in air. It is a silvery-grey metal, and is malleable, ductile, and soft enough to be cut with a knife. It is a rare earth metal found in cerite, gadolinite and monazite. The element itself was isolated only recently.