CBSE NOTES CLASS 12 PHYSICS
CHAPTER 13 NUCLEUS
α-rays consists of α-particles, which are doubly ionised helium ion.
When an α-particle is emitted by a nucleus its atomic number decreases by 2 and mass number decreases by 4.
Total mass of RHS is less than that of LHS.
The disintegration energy or the Q-value of a nuclear reaction is the difference between the initial mass energy and the total mass energy of the decay products. For α-decay
Q is also the net kinetic energy gained in the process or, if the initial nucleus X is at rest, the kinetic energy of the products, Q > 0 for exothermic processes such as α-decay.