Binding energy

The binding energy of a nucleus is the energy that would be needed to split up the nucleus into separate nucleons .

Example

We calculate the binding energy of the He-4 nucleus

This nucleus consists of 2 protons en 2 neutrons

Mass  of the 4 particles     : 2 x 1.007276 u + 2 x 1.008665 u = 4.031882 u       

Mass of the nucleus           :  4.002603 u – 2 x 0.00054858 u = 4.00150584 u            

Mass defect Δm                   :  0.03037616 u

Binding energy                    :  E= Δm.c² =  (0.03037616 x 1.66054 x10^-27) (2.99792458 x 10⁸)² = 4.546664 x 10^-12 J = 2.8417 x 10⁷ eV = 28.42 MeV

Binding energy  per nucleon = 7.10 MeV

Remark : The smaller the mass per nucleon the more stable the nucleus.