Question

What happens to the position of an element in the periodic table when it emits
(a) an $\alpha$-particle,
(b) $\beta$-particle and
(c) $\gamma$-radiation? Give reason for your answer.

Answer 1

Alpha ($\alpha$) emission :
When an alpha particle is emitted, the atomic number Z of the parent atom decreases by 2 units.
${}_Z{X}^A\to {}_{Z-2}{X}^{A-4}+{}_{2}H{e}^4$
Therefore, the new element has properties similar to those of an element two places to its left in the periodic table.
Beta ($\beta$) emission :
When a beta particle is emitted, the atomic number Z increases by one unit.
${}_Z{X}^A\to {}_{Z+1}{X}^A+{}_{-1}{e}^0$
As a result, the new element has properties similar to those of an element one place to its right in the periodic table.
Gamma ($\gamma$) emission :
The $\gamma$-ray takes away no mass and no electric charge from the nucleus i.e., no neutrons or protons are lost, hence the nucleus does not decay into a different one.
${}_Z{X}^A\to {}_Z{X}^A+{}_0{\gamma }^0$
The atomic number Z and mass number A, both remain constant. So, the daughter element shows the same properties as the parent element.