Question

The second ionization potentials in electron volts of oxygen and fluorine atoms are respectively given by -

• A. 35.1., 38.3
• B. 38.3, 38.3
• C. 38.3, 35.1
• D. 35.1, 35.1

Answer 1

The correct option is C

38.3, 35.1

Second ionisation potential is the energy required to remove an electron from unipositively charged ion

0 $\to$ E.C 1 $s^2$ 2 $s^2$ 2 $p^4$ $O^{+}$ - 1 $s^2$ 2 $s^2$ 2 $s^3$

F $\to$ E.C 1 $s^2$ 2 $s^2$ 2 $p^5$ $F^{+}$ - 1 $s^2$ 2 $s^2$ 2 $p^4$

0 $\to$ $O^{+}$ $I.P_2$ F $\to$ $F^{+}$ $I.P_2$

0 $\to$ $O^{+2}$ $I.P_2$ $I^{+}$ $\to$$I^{+2}$ $I.P_2$

$I.P_1$ of F > O as fluorine has less atomic size compared to O.

$I.P_2$ of O > F as $O^{+}$ has filled P- sub shell.