I'm sorry for posting this another thread, but I accidentally posted under to wrong forum initially and could not figure out how to delete it :-( 1. The problem statement, all variables and given/known data Find the missing isotope: Iodine-127 (n, alpha) My answer is Sb- 122 but it was wrong. Also, how would I go about finding the number of alpha and (negative) beta decay reactions needed to reduce an isotope, if I am not given half life? Please help! I know I am probably making it harder than it has to be! 2. Relevant equations I am having a bit of trouble applying nuclear decay reactions. I understand the differences between alpha, beta, and gamma, but cannot seem to solve the equations 100% of the time. I do not know how I would type out alpha, beta, and gamma here, though. So I will just say that given alpha, I know to subtract, and Beta can be positive or negative. Gamma has no addition or subtraction. 3. The attempt at a solution I wonder if I am just not comprehending what (n,alpha) means. Set up in a way to identify the particles is easy for me, though. As for the question pertaining to the cascade, we never reviewed a problem like that and therefore I would really appreciate someone just offering me a starting point.