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:

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

An isotope of protactinium (symbol $\mathrm{Pa}$) has$91$ protons and $140$ neutrons in its nucleus. The nuclide decays by alpha decay to become an isotope of actinium (symbol $\mathrm{Ac}$). Write a complete decay equation for this decay.

Some data for an experiment is shown in the table

Explain what you can conclude from the difference in readings between the columns.