Geiger counters, film badges and spark counters are all used to detect nuclear radiation. What do they all have in common, in the way they perform their function?

The equation shows how an isotope of radium decays to become an isotope of radon.

${}_{88}{}^{223}\mathrm{Ra}\to {}_{86}{}^{219}\mathrm{Rn}+{}_2{}^4\mathrm{H}+\mathrm{energy}$

Here, we can check that the equation is balanced by counting the number of nucleons before and after the decay, and the number of protons before and after.

For the nucleons, we have $223=219+4$.

Show that the number of protons is the same before and after the decay.

The equation shows how an isotope of carbon decays to become an isotope of nitrogen.

${}_6{}^{15}\mathrm{C}\to {}_7{}^{15}\mathrm{N}+{}_{-1}{}^0\mathrm{e}+\mathrm{energy}$

Show that this equation is balanced.

What is $A$ and $B$ in the following decay equation, which shows how an isotope of polonium decays to become an isotope of lead:

${}_{84}{}^{211}\mathrm{Po}\to {}_{82}{}^{207}\mathrm{Pb}+A+B$