Kinetic isotope effect both results are large enough to be indicative of weakening of the C-N bond in the transition state that would occur in a concerted process. Since kinetic isotope effects arise from differences in isotopic masses, the largest observable kinetic isotope effects are associated with isotopic substitutions of hydrogen with deuterium (100% increase in mass) or tritium (200% increase in mass). Kinetic isotope effects from isotopic mass ratios can be as large as 36.4 using muons. They have produced the lightest hydrogen atom, H (0.113 amu), in which an electron orbits around a positive muon (μ) "nucleus" that has a mass
Isotope (counting as stable), and 26 elements have only a single stable isotope (of these, 19 are so-called mononuclidic elements, having a single primordial stable isotope that dominates and fixes the atomic weight of the natural element to high precision; 3 radioactive mononuclidic elements occur as well). In total, there are 253 nuclides that have not been observed to decay. For the 80 elements that have one or more stable isotopes, the average number of stable isotopes is 253/80 = 3.1625 isotopes per element. The proton:neutron ratio is not the only factor affecting nuclear stability. It depends also on evenness or