After the discovery of the atomic nucleus, it was immediately clear that it is it that undergoes transformations during radioactive decays. After all, there are no α-particles on electronic shells. and reducing the number of electrons in the shell turns the atom into an ion. not a new chemical element.
The rule of displacement. Transformations of nuclei follow the so-called displacement rule, formulated for the first time by Soddy: during α-decay, the nucleus loses the positive charge 2E, and its mass decreases by about four atomic units of mass. As a result, the element is shifted by two cells to the beginning of the Periodic system. It is written like this:
Here the element is indicated by common symbols. The core charge is indicated as an index at the bottom left of the element symbol, and the atomic mass is indicated as an index at the top left of the symbol. For the α-particle, which is the nucleus of the helium atom, the designation nuclear Physicist Radioactivity is used.
In β-decay, the atom loses an electron. As a result, the charge of the core increases by one, the mass remains almost unchanged:
Here the Physics of the atomic nucleus Radioactivity denotes an electron: the index 0 at the top means that its mass is very small compared to the atomic unit of mass. After β-decay, the element shifts one cell closer to the end of the Periodic system.
Gamma radiation is not accompanied by a change in charge; the mass of the nucleus changes negligibly.