Calculate the defect of helium nucleus

1 amu=1.67×10  

−27

kg

Using this and Einsteins relation, we get the energy equivalent to the rest mass as:

E=mc  

2

=(1.67×10  

−27

×0.0304)×(3×10  

8

)  

2

=4.569×10  

−12

J

Converting this energy in electron volts.

E=  

1.6×10  

−19

4.569×10  

−12

=28MeV

This is per nucleon of Helium. One Helium nucleus has four nucleons.

it is to be noted that an alpha particle is an helium nucleus. so it contains 2 protons 2 neutrons and has a mass number of 4. when alpha decay particles are ejected from the nucleus it gets transformed into an atom which has atomic number less than 2 and a mass number less than 4.

an equation that could represent alpha decay is radium 226 decay of alpha particle forms radon 222.

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