 Antimony has two stable isotopes : 121Sb with a natural abundance of 57 @.@ 36 % and 123Sb with a natural abundance of 42 @.@ 64 % . It also has 35 radioisotopes , of which the longest @-@ lived is 125Sb with a half @-@ life of 2 @.@ 75 years . In addition , 29 metastable states have been characterized . The most stable of these is 120m1Sb with a half @-@ life of 5 @.@ 76 days . Isotopes that are lighter than the stable 123Sb tend to decay by β + decay , and those that are heavier tend to decay by β − decay , with some exceptions . 
 Antimony <a href='got' title='1'><mark>has</mark></a> two stable isotopes : 121Sb with a natural abundance of 57 @.@ 36 % and 123Sb with a natural abundance of 42 @.@ 64 % . It also <a href='got' title='2'><mark>has</mark></a> 35 radioisotopes , of which the longest @-@ lived <a href='drop_aux' title='3'><mark>is</mark></a>125Sb with a half @-@ life of 2 @.@ 75 years . In addition , 29 metastable states <a href='been_done' title='4'><mark>have</mark></a> been characterized . The most stable of these <a href='drop_aux' title='5'><mark>is</mark></a>120m1Sb with a half @-@ life of 5 @.@ 76 days . Isotopes <a href='null_relcl' title='6'><mark>that</mark></a><a href='drop_aux' title='7'><mark>are</mark></a>lighter than the stable 123Sb tend to decay by β + decay , and those <a href='null_relcl' title='8'><mark>that</mark></a><a href='drop_aux' title='9'><mark>are</mark></a>heavier tend to decay by β − decay , with some exceptions . 
Antimony got two stable isotopes : 121Sb with a natural abundance of 57 @.@ 36 % and 123Sb wid a natural abundance of 42 @.@ 64 % . It also got 35 radioisotopes , of which the longest @-@ lived 125Sb with a half @-@ life of 2 @.@ 75 yrs . In addition , 29 metastable states done been characterized . The most stable of dem 120m1Sb with a half @-@ life of 5 @.@ 76 dayz . Isotopes lighter than the stable 123Sb tend to decay by β + decay , and those heavier tend to decay by β − decay , with some exceptions .