Answer:
1. Co^2+ 1s2 2s2 2p6 3s2 3p6 3d7
2. N^3- 1s2 2s2 2p6
3. Ca^2+ 1s2 2s2 2p6 3s2 3p6
Explanation:
When Cobalt loses 2 electrons to become Co2+ it loses the electrons which are in 4s2, not the ones in 3d7 because the electrons in 4s2 have a high reactivity. Thus, when electrons are lost from Co atom, they are lost from the 4s orbital first because it is actually higher in energy when both 3d and 4s are filled with electrons.
