Isotopes of thulium

Thulium (Tm) is a chemical element with the atomic number 69. It has several isotopes, of which the most notable are: 1. **Tl-169**: This is the most stable and abundant isotope of thulium, making up nearly all naturally occurring thulium. It has a half-life of 1,457 years and is stable. 2. **Tl-168**: This isotope is radioactive and has a half-life of about 93 minutes.