Q44 / 180 · AIIMS 2001 · Chemistry

Which of the following has highest second ionization energy?

  • A
    $\mathrm{Ni}$
  • B
    $\mathrm{V}$
  • Correct answer
    C
    $\mathrm{Cr}$
  • D
    $\mathrm{Mn}$

Solution

Electronic configuration for chromium is : $$ { }_{24} \mathrm{Cr} \rightarrow 1 s^2 2 s^2 2 p^6 3 s^2 3 p^6 3 d^5 4 s^1 $$ After ionisation of $4 s$ electron the next electron which will be ionised is from $3 d$ orbital. As $3 d^5$ electronic configuration, is stable, hence, the second ionisation of $\mathrm{Cr}$ will require much greater ionisation energy than the expected one.

Hence, the correct answer is option: 'C'.

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