Lead 206 (Pb)
Lead 206 and lead 207.
Isotopes of lead are the final products of the decay chain of uranium.
The uranium decay chain ends with lead stable isotopes.
Uranium itself is a radioactive and toxic element. All the elements from the decay chain of uranium isotopes are also radioactive (ex.: radon, radium, etc.) excepting the final product, an isotope of lead.
Lead 206 (Pb)
All radioactive elements eventually decay to lead (Pb). There a numerous isotopes of lead and it is thought that all the lead(Pb) in the world is derived from decayed radioactive isotopes.
The final product of the decay chain is the stable isotope 206Pb.
It is not yet discovered since all of the uranium isotopes are having half life for several millions of years. We would be able to find it after atleast 700 millions of years.
If we use uranium-238 as our starter isotope, what happens is that a nuclear decay event happens (in this case an alpha decay) and the U-238 transforms into a daughter isotope thorium (Th-234). The half-life of this transition is 4.5 billion years. Thorium-234 then undergoes a decay. And the process continues until a stable isotope is created as the last daughter of a decay chain. Note that there will be different half lives for the transition events, and the modes of decay will vary depending on what daughter is now the parent in the next decay event. Use the link below to see all the steps. The chart will show the whole chain including the half-life of isotope undergoing decay, the decay mode, and the daughter. Follow along using the keys and the process will reveal itself.
Uranium 238 is a natural isotope of uranium, non-fissionable with thermal neutrons, with an atomic mass of 238,050 788 247 ± 0,000 002 044 u.a. and a half life of 4,468 x 109 years, atomic number 92. Natural uranium contain 99.2745 % U 238 (atomic); the desintegration of U 238 is alpha type.
The final product is not radioactive.
The final product is a stable isotope, but what it is depends on the decay. The intermediate steps constitute what is called a decay chain. For example, one well known decay chain is that of thorium-232, which goes through a series of radioactive isotopes decaying each to the next. The final product is lead-208, which stops the process since it is stable and does not decay further. Other decay chains produce other results. Sometimes the first decay produces a stable result, as in the case of tritium, which decays to helium-3.