Question

A neutral atom $Ar$ is converted to ${Ar}^{3+}$ by the following process:
$Ar\left(g\right)\underset{E_1}{\overset{-e}{\to }}{Ar}^{+}\left(g\right)\underset{E_2}{\overset{-e}{\to }}{Ag}^{2+}\left(g\right)\underset{E_3}{\overset{-e}{\to }}{Ar}^{3+}\left(g\right)$
The correct order of $E_1,E_2$ and $E_3$ energies are

• A. $E_1<E_2<E_3$
• B. $E_1>E_2>E_3$
• C. $E_1=E_2=E_3$
• D. $E_1>E_2<E_3$

Answer 1

The correct option is A $E_1<E_2<E_3$

When an electron is removed from an isolated gaseous atom, some energy is required which is known as ionisation energy. After removal of one electron, no. of electrons in the atom or ion decreases but nucleus charge is same. Now, the remaining electrons will observe more nuclear force than before as effective nucleus charge increases, thus, more energy is required to remove the first electron.

$Ar\underset{E_1}{\overset{-e^{-}}{\to }}A{r}^{+}\underset{E_2}{\overset{-e^{-}}{\to }}A{r}^{+2}\underset{E_3}{\overset{-e^{-}}{\to }}A{r}^{+3}$

On removing the electron, the effective nuclear charge increases on each electron. Thus more energy is required.

$\therefore E_1<E_2<E_3$

Hence , option A is correct .