Isotopes of lead

Lead (Pb) has four stable isotopes - 204Pb, 206Pb, 207Pb, 208Pb and one common radiogenic isotope 202Pb with a half-life of ~53,000 years. The standard atomic mass is 207.2(1) u. It is the heaviest discovered element to have a stable isotope. (The more massive 209Bi, long considered to be stable, actually has a half-life of 1.9×1019 years)

Isotopes of lead occurring within the radioactive disintegration chains of actinium, radium, and thorium were known as
 * radium G: 206Pb
 * actinium D: 207Pb
 * thorium D: 208Pb
 * radium D, radio-lead or radiolead: 210Pb
 * actinium B: 211Pb
 * thorium B: 212Pb
 * radium B: 214Pb

206Pb being the end of the Uranium/Radium series from U-238.

207Pb being the end of the Actinium series from U-235.

208Pb being the end of the Thorium series from Th-232.