Question

What is the binding energy of nitrogen?

Answer 1

Step 1. A number of neutrons and protons:

${}_7{}^{14}\mathrm{N}$ nucleus is made up of $7$ protons and $7$ neutrons.

Step 2. Calculating the mass of nucleons forming the nucleus:
Mass of nucleons forming the nucleus $=7m_p+7m_n$
$$\begin{gathered} =\text{Mass of}7\text{protons}+\text{Mass of}7\text{neutrons} \\ =7\times 1.00783+7\times 1.00867\mathrm{u} \\ =7.05431+7.06069\mathrm{u} \\ =14.11550.\mathrm{u} \end{gathered}$$
Mass of nucleus, ${\mathrm{m}}_{\mathrm{N}}=14.00307\mathrm{u}$
Step 3. Calculating the mass defect:

Therefore,
Mass defect $$\begin{gathered} =14.11550-14.00307 \\ =0.11243a.m.u \end{gathered}$$
Energy equivalent to mass defect$$\begin{gathered} =0.11243\times 931 \\ =104.67\mathrm{MeV} \end{gathered}$$

Hence, the binding energy of nitrogen $=104.67MeV.$