Question

a nucleus pt emits alpha particles and change to u which emits beta particleand then gamma partcle change into pb 235 93 write nuclear changes in form of equation stating atomic and mass no​

Answer 1

Answer:

An alpha particle is a helium nucleus 42He. Whenever a nucleus goes through alpha decay, it transforms into a different nucleus by emitting an alpha particle. For example, when 23892U undergoes alpha-decay, it transforms into 23490Th.

23892U → 23490Th + 42He … (1)

Now, 42He contains two protons and two neutrons. Hence, after emission, the mass number of the emitting nucleus reduces by four and the atomic number reduces by two. Therefore, the transformation of AZX nucleus to A-4Z-2X nucleus is expressed as follows,

AZX → A-4Z-2X + 42He … (2)

where AZX is the parent nucleus and A-4Z-2X is the daughter nucleus. It is important to note that the alpha decay of 23892U can occur without an external source of energy. This is because of the total mass of the decay products (23490Th and 42He) < the mass of the original 23892U

Or, the total mass-energy of the decay products is less than that of the original nuclide. This brings us to the concept of ‘Q value of the process’ or ‘Disintegration energy’ which is the difference between the initial and final mass-energy of the decay products. For an alpha decay, the Q value is expressed as,

Q = (mX – mY – mHe) c2 … (3)

This energy is shared between the daughter nucleus, A-4Z-2X and the alpha particle, 42He in the form of kinetic energy. Also, alpha decay obeys the radioactive laws.