Long description

This diagram demonstrates the radioactive decay of uranium-238. On the left of the diagram is the 'parent nucleus', uranium, mass number 238, proton number 92. Beside this is a small 'explosion' graphic labelled as the 'decay event'. Two arrows lead away from the parent nucleus and decay event. One arrow leads to 'daughter nucleus', thorium, mass number 234, proton number 90. The second arrow leads to 'emitted α (alpha) particle', helium, mass number 4, proton number 2.