## Chemistry: Molecular Approach (4th Edition)

The electronc configuration of $Fe$ is $[Ar] 3d^6 4s^2$. So, $Fe^{2+}$ has two less electrons; hence its electronic configuration is $Fe$ is $[Ar]4s^0 3d^6$ **Note, the electrons are taken out of the 4s sub shell before the 3d sub shell.