How does alpha decay work?
During alpha decay, a nucleus emits a particle that consists of two protons and two neutrons — an alpha (α) particle, which is also a helium nucleus.
Since the atom loses two protons, it changes to a different element.
Its atomic number (
The atom loses two nucleons (protons and neutrons), so its mass number (
For example, an atom of uranium-238 (with 92 protons) becomes an atom of thorium-234 (with 90 protons) when it undergoes alpha decay.