# What are some common mistakes students make with nuclear equations?

May 16, 2018

A typical mistake is to add backwards... This tends to occur when rushing. To remedy this, simply make the effort to write out the system of equations by reading from left to right, using conservation of mass.

Consider solving for the daughter nuclide of the following positron emission of $\text{_(7)^(13) "N}$:

${\text{_(7)^(13) "N" -> ""_(1)^(0) e + ? + }}_{0}^{0} \overline{\nu}$

Some students might accidentally report oxygen-13 instead of carbon-13, whereas it can be seen that it should be carbon-13:

${\text{_(7)^(13) "N" -> ""_(1)^(0) e + ""_(6)^(13) "C" + }}_{0}^{0} \overline{\nu}$

To do this, one would set up a simple system of equations for the mass number and atomic number:

$13 = 0 + A + 0$

$7 = 1 + Z + 0$

From this, it readily follows that the mass number is $13$ and the atomic number is $6$, indicating carbon and not oxygen.