Hi, I am struggling with a question where they want me to determine whether or not three different decay are allowed. From what I have understood all decays must follow a set of conservation law. These laws are: 1 Conservation of Baryon number 2 Conservation of Lepton number 3 Conservation of electric charge This is very straight forward when you have simple decays like the decay of a neutron. Where you have: n -> p+e+anti ve But how does it work for nucleons? For example: Thorium-222 -> Oxygen-16 + Lead-206 This decay is not allowed as thorium-222 only decays with alpha-decay. But as far as I can see the laws are still followed. 1: 222 -> 16 + 206 = 222 2: 90 -> 8 + 82 = 90 3: 90-90 -> 8-8 + 82-82 = 0 What am I missing? please help!