Calculation for 1a.m.u (atomic mass unit)

 Calculations for 1 a.m.u.:

 

        Calculated mass of Helium Nucleus

        Mass of Proton             2 x 1.0078=       2.0156

        Mass of Neutron          2 x 1.0087=        2.0174

                                                                        4.0330

        Actual mass of Helium Nucleus      (-)   4.0026

        Difference of the Mass                           0.0304

        Binding Energy of the Helium atom= 0.0304 x 931.5 = 28.3176MeV

1 a m u = 1.66 x 10 ^{– 24} g or 1.66 x 10^-27 Kg.  

1 mole of a particle (proton or neutron) = 1 g.

        6.023 x 10 ²³ particles = 1g.

Mass of 1 particle

Mass of 12 particles or mass of ₆C¹² 

                             = 12 x 

E = mc²

          = 1.66 x 10 ^{– 27} Kg x (3 x 10⁸)² m/sec

         = 1.66 x 10 ^{– 27}  x 9 x 10¹⁶ Kg-m/sec

         = 14.94 x 10 ^{– 11} J

         = 1.494 x 10 ^{– 10} J or  1.5 x   10 ^{– 10}  J

1eV. = 1.602 x 10^{- 19} J

Ernest Lawrence invented a device to accelerate the electron called cyclotron.

The energy absorbed by an electron when it accelerated towards a - ve electrode.

eV = 1.602 x 10 ^{– 19} Coulombs       

E = 1.602 x 10 ^{– 19}  e x 1 V                                                     

 = 1.602 x 10 ^{– 19‑} Coulomb – Volt (Joules)

 = 1.602 x 10 ^{– 19} 

1.494 x 10 ^{– 10} J = 1 a.m.u

But, 1eV = 1.602 x 10 ^{– 19} J

1.602 x 10 ^{– 19} J =

1eV = 1. 062 x 10 ^{– 19} x 10¹⁰ amu

                     = 0.936 x 10⁹ eV

                     = 936.3 x 10⁶ MeV

                     = 936.3 MeV

The nuclear force is strong and a short-range force that acts between the particles having distance between them = 10 ^{– 15} m or 1 fm.

N/Z (ratio between the mass of neutrons and atomic number) increases stability decreases.

e.g.:  N/Z ratio for Uranium ( ₉₂U²³⁸) is 146/92 = 1.6.