Natural lead consists of four stable isotopes with mass numbers of 204, 206, 207, and 208, and traces of five short-lived radioisotopes.
The high number of isotopes is consistent with lead's atomic number being even.
Lead has a magic number of protons (82), for which the nuclear shell model accurately predicts an especially stable nucleus.
Lead-208 has 126 neutrons, another magic number, which may explain why lead-208 is extraordinarily stable.

With its high atomic number, lead is the heaviest element whose natural isotopes are regarded as stable; lead-208 is the heaviest stable nucleus. (
This distinction formerly fell to bismuth, with an atomic number of 83, until its only primordial isotope, bismuth-209, was found in 2003 to decay very slowly.)
The four stable isotopes of lead could theoretically undergo alpha decay to isotopes of mercury with a release of energy, but this has not been observed for any of them; their predicted half-lives range from 10³⁵ to 10¹⁸⁹ years (at least 10²⁵ times the current age of the universe).

Three of the stable isotopes are found in three of the four major decay chains: lead-206, lead-207, and lead-208 are the final decay products of uranium-238, uranium-235, and thorium-232, respectively.
These decay chains are called the uranium chain, the actinium chain, and the thorium chain.
Their isotopic concentrations in a natural rock sample depends greatly on the presence of these three parent uranium and thorium isotopes.
For example, the relative abundance of lead-208 can range from 52% in normal samples to 90% in thorium ores; for this reason, the standard atomic weight of lead is given to only one decimal place.
As time passes, the ratio of lead-206 and lead-207 to lead-204 increases, since the former two are supplemented by radioactive decay of heavier elements while the latter is not; this allows for lead–lead dating.
As uranium decays into lead, their relative amounts change; this is the basis for uranium–lead dating.
Lead-207 exhibits nuclear magnetic resonance, a property that has been used to study its compounds in solution and solid state, including in human body.

Apart from the stable isotopes, which make up almost all lead that exists naturally, there are trace quantities of a few radioactive isotopes.
One of them is lead-210; although it has a half-life of only 22.3 years, small quantities occur in nature because lead-210 is produced by a long decay series that starts with uranium-238 (that has been present for billions of years on Earth).
Lead-211, -212, and -214 are present in the decay chains of uranium-235, thorium-232, and uranium-238, respectively, so traces of all three of these lead isotopes are found naturally.
Minute traces of lead-209 arise from the very rare cluster decay of radium-223, one of the daughter products of natural uranium-235, and the decay chain of neptunium-237, traces of which are produced by neutron capture in uranium ores.
Lead-210 is particularly useful for helping to identify the ages of samples by measuring its ratio to lead-206 (both isotopes are present in a single decay chain).

In total, 43 lead isotopes have been synthesized, with mass numbers 178–220.
Lead-205 is the most stable radioisotope, with a half-life of around 1.73×10⁷ years.
The second-most stable is lead-202, which has a half-life of about 52,500 years, longer than any of the natural trace radioisotopes.
Natural lead consists of four stable isotopes with mass numbers of 204, 206, 207, and 208, and traces of five short-lived radioisotopes. The high number of isotopes is consistent with lead's atomic number being even. Lead has a magic number of protons (82), for which the nuclear shell model accurately predicts an especially stable nucleus. Lead-208 has 126 neutrons, another magic number, which may explain why lead-208 is extraordinarily stable.
With its high atomic number, lead is the heaviest element whose natural isotopes are regarded as stable; lead-208 is the heaviest stable nucleus. (This distinction formerly fell to bismuth, with an atomic number of 83, until its only primordial isotope, bismuth-209, was found in 2003 to decay very slowly.) The four stable isotopes of lead could theoretically undergo alpha decay to isotopes of mercury with a release of energy, but this has not been observed for any of them; their predicted half-lives range from 10³⁵ to 10¹⁸⁹ years (at least 10²⁵ times the current age of the universe).
Three of the stable isotopes are found in three of the four major decay chains: lead-206, lead-207, and lead-208 are the final decay products of uranium-238, uranium-235, and thorium-232, respectively. These decay chains are called the uranium chain, the actinium chain, and the thorium chain. Their isotopic concentrations in a natural rock sample depends greatly on the presence of these three parent uranium and thorium isotopes. For example, the relative abundance of lead-208 can range from 52% in normal samples to 90% in thorium ores; for this reason, the standard atomic weight of lead is given to only one decimal place. As time passes, the ratio of lead-206 and lead-207 to lead-204 increases, since the former two are supplemented by radioactive decay of heavier elements while the latter is not; this allows for lead–lead dating. As uranium decays into lead, their relative amounts change; this is the basis for uranium–lead dating. Lead-207 exhibits nuclear magnetic resonance, a property that has been used to study its compounds in solution and solid state, including in human body.
Apart from the stable isotopes, which make up almost all lead that exists naturally, there are trace quantities of a few radioactive isotopes. One of them is lead-210; although it has a half-life of only 22.3 years, small quantities occur in nature because lead-210 is produced by a long decay series that starts with uranium-238 (that has been present for billions of years on Earth). Lead-211, -212, and -214 are present in the decay chains of uranium-235, thorium-232, and uranium-238, respectively, so traces of all three of these lead isotopes are found naturally. Minute traces of lead-209 arise from the very rare cluster decay of radium-223, one of the daughter products of natural uranium-235, and the decay chain of neptunium-237, traces of which are produced by neutron capture in uranium ores. Lead-210 is particularly useful for helping to identify the ages of samples by measuring its ratio to lead-206 (both isotopes are present in a single decay chain).
In total, 43 lead isotopes have been synthesized, with mass numbers 178–220. Lead-205 is the most stable radioisotope, with a half-life of around 1.73×10⁷ years. The second-most stable is lead-202, which has a half-life of about 52,500 years, longer than any of the natural trace radioisotopes.
Lead