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?

1 Answer

The electron configuration must finish like this: #4s^2 3d^8# .

Explanation:

The element is Nickel (#"Ni"#) with #28# valence eletrons.

The period is identified looking at the level of energy (#n#) which is the number #4#, for the #4s# orbital. This means #"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 #"VIIIB"# (e.g. #"Fe", "Co", "Ni"#, . . . ).