Question

What is the group number, period and block of the element with atomic number $40$?

Answer 1

Atomic number=$40$

Electronic configuration=$1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}5s^{2}4d^2$

Group number=number of $e^{-}$ in $(n-1)d+$ no. of $e^{-}$ in valence shell.

$=2+2=4$

Period number=Principal quantum number of the valence shell

$=5$