Write the beta decay reaction of lead 209/82 Pb.

Beta decay of a nucleus is the formation of an electron and a new atom. An electron has a negative (-1) charge and has no mass. As a result of beta decay, an atom is formed with almost the same mass and the charge of the nucleus is greater by 1. Therefore, if 20982Pb undergoes decay, an element with a charge of 82 + 1 = 83 is formed as a result.

According to the periodic table, there is only one element that can have a charge equal to 83, this element is bismuth (denoted by Bi). Therefore, you can write down the reaction:

209 / 82Pb → 209 / 83Bi + 0-1e.