# How does alpha decay change the nucleus of an atom?

Apr 15, 2016

${U}^{238}$ -> $T {h}^{234} + H {e}^{4}$
Uranium has an atomic number of 92, thotium an atomic number of 90, and we see the decrease by 4 in mass number. $H {e}^{4}$ is the alpha patticle, which is also a helium-4 nucleus.