<page_title> Isotopes of thallium </page_title> <section_title> List of isotopes </section_title> <table> <cell> 202Tl <col_header> nuclide symbol </col_header> <col_header> excitation energy </col_header> </cell> <cell> 12.23(2) d <col_header> half-life </col_header> </cell> <cell> 204Tl <col_header> nuclide symbol </col_header> <col_header> excitation energy </col_header> </cell> <cell> 3.78(2) y <col_header> half-life </col_header> </cell> </table>
Thallium-202 has a half-life of 12.23 days and thallium-204 has a half-life of 3.78 years.