Question

Second ionization energies of chromium and copper are larger than those of their neighbouring elements $(V, Mn, Ni, Zn )$. It is due to the fact that

• A. Second electron in each case is removed from $4 s$ orbital
• B. Second electron is removed from stable half-filled $3 d$ sub-orbit in case of chromium and from stable completely filled $3 d$ sub-robit in case of copper
• C. Electrode potential of these elements ( $Cr$ and $Cu$ ) are higher than those of their neighbouring elements
• D. Their atomic radii are different due to screening effect

Answer 1

Answer: (B)

Both are stable configuration and removal of next electron requires very high energy. Thus, second IE is very high
$V ^{+}[ Ar ] 3 d^3 4 s^1$ ) Second electron is removed for
$Mn ^{+}[ Ar ] 3 d^5 4 s^1$ ) $4 s$ subshell, thus, second IE is
$Ni ^{+}[ Ar ] 3 d^8 4 s^1$ ) low
$\left.Zn ^{+}[\text{Ar}] 3 d^{10} 4 s^1\right)$