In a decay chain of radioactive substances, the daughter nuclide followed by the grandchild nuclide are the decay products of a parent nuclide. Example: iodine-137 (parent nuclide) decays via xenon-137 (daughter), caesium-137 (grandchild), barium-137m (great-grandchild) into the stable barium-137 (great-great-grandchild). (See also ‘decay chain, natural’)

Parent / daughter / grandchild nuclides in the decay chain of iodine-137 to barium-137