21. By Dec . 17 they had worked out the complete decay chain for their new element. 22. Nihonium was discovered in the decay chain of moscovium, which produced a few precious atoms of nihonium. 23. Each decay chain has a unique half-life, which means the daughter isotopes are generated at different rates. 24. Much smaller trace amounts of the short-lived nuclear isomer protactinium-234m occur in the decay chain of uranium-238. 25. After prompt fission neutron emission the residual fragments are still neutron rich and undergo a beta decay chain . 26. Alpha particles that produce nucleogenic reactions come from natural alpha particle emitters in uranium and thorium decay chains . 27. Three elements and their decay chains are responsible for the radiation emitted by rock : potassium, thorium and uranium. 28. Of the 94 naturally occurring elements, 83 are primordial and 11 occur only in decay chains of primordial elements. 29. Unlike all the other intermediate elements in the aforementioned decay chains , radon is, under normal conditions, gaseous and easily inhaled. 30. U-series isotopes are unique amongst radiogenic isotopes because, being in the U-series decay chains , they are both radiogenic and radioactive.
