# How can we identify the number of group from electronic configration of any element if it ended in 3d^8 4S^2 I know group no. = total no. of valence but whats the valence here in this situation?

Jun 5, 2017

The electron configuration must finish like this: $4 {s}^{2} 3 {d}^{8}$ .
The element is Nickel ($\text{Ni}$) with $28$ valence eletrons.
The period is identified looking at the level of energy ($n$) which is the number $4$, for the $4 s$ orbital. This means $\text{Ni}$ is in the fourth period in the periodic table.
The group number is normally related to the valence electrons. However, this relation does not include the transition metals from group $\text{VIIIB}$ (e.g. $\text{Fe", "Co", "Ni}$, . . . ).