Electron capture is a form of beta decay in which the nucleus of a radionuclide captures an electron. In the case of mercury-201, the equation below illustrates that
²⁰¹₈₀Hg + ⁰₋₁e ⇒ ²⁰¹₇₉Au
As can be seen above, the electron capture reduces the atomic number by one unit leading to the production of a new radioisotope (because of the change in atomic number).
