Question

The mass of the atom 23
                                     11 Na is 22.9898 amu.
a) Calculate its binding energy per atom in millions of electron volts.
b) Calculate its binding energy per nucleon.

Answer 1

a) m = theoretical mass = Z X m_H + (A - Z) m_n

where, Z = atomic number, A = mass number,  m_H = mass of proton, m_n = mass of nutron

mass of proton = 1.007825 u . mass of nutron = 1.008665 u

Z for Cu = 23 then (A - Z ) = 23 - 11 = 22

substitute value

( 11X 1.007825) + (12 X 1.008665) = 23.190055 u

m = m - m' where, m = mass defect

= 23.190055 - 22.9898 = 0.200255 u

binding energy = m X 931.5

= 0.200255 X 931.5 = 186.5375325 MeV

Binding energy per atom = 186.5375325 MeV

b) binding energy/nucleon = binding energy/ mass number

=  186.5375325 / 23

= 8.11 MeV

binding energy/nucleon = 8.11 MeV