What happens to the mass of atoms during a nuclear reaction.

In nuclear reactions one type of sub-atomic particle change into another, this destabilizes the nucleus forcing it to split and release a certain amount of energy in the form of massless particles

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because u need two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei to form isotopes.

so since they all have the same shape? i mean maybe because m& m and reeses are both chocolates