Question

If first ionization potential of an atom is 16 V then determine the first excitation potential value for it.

• A. 12 V
• B. 14 V
• C. 19 V
• D. 20 V

Answer 1

The correct option is A 12 V

First ionisation potential is the amount of energy which supplied to escape electron from the field of the nucleus of the atom.

We can assume this as a transition from 1st orbit $n=1$ to the infinite orbit $n=\infty$,

$E_{\infty }-E_1=16eV$

But we know that, $E_n\propto \frac{1}{n^2}$,

ie, $E_1=-16eV$

and for the first transition/excitation from $n=1$ to $n=2$,

required energy will be,

$E_2-E_1=\frac{-16}{2^2}-(-16)$

$E_2-E_1=12eV$,

Hence, the correct option is $A$