Question

What is the electron configuration of Cd2+?

Answer 1

`["Kr"]4d^10`

Explanation:

Your starting point here will be the electron configuration of a neutral cadmium atom.

Cadmium, `"Cd"`, is located in period 5, group 12 of the periodic table and has an atomic number equal to `48`. This means that a neutral cadmium atom will have a total of `48` electrons surrounding its nucleus.

This also tells you that the `"Cd"^(2+)` cation, which has two electrons less than the neutral atom, will have a total of `46` electrons.

So, the electron configuration of a neutral cadmium atom looks like this

`"Cd: " 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 4p^6 4d^10 5s^2`

Alternatively, you can use the noble gas shorthand notation to write cadmium's electron configuration based on that of krypton, the noble gas that comes before cadmium in the periodic table

`"Cd: " ["Kr"] 4d^10 5s^2`

Now, the `"Cd"^(2+)` cation is formed when cadmium loses the electrons that are highest in energy. As you can see in the electron configuration, the two electrons that occupy the 5s-orbital match this profile.

Therefore, the electron configuration of the `"Cd"^(2+)` cation will be

`"Cd"^(2+): ["Kr"] 4d^10`