Nickel atom can lose two electrons to form Ni2+ ion. The atomic number of nickel is 28. From which orbital will nickel lose two electrons?


Ni28=1s2,2s2,2p6,3s2,3p6,3d8,4s2; Nickel will lose 2 electrons from 4s (outermost shell) to form Ni2+ ion.
Hence, Ni2+28=1s2,2s2,2p6,3s2,3p6,3d8,4s0