given a periodic table,all we need to know write the electronic configuration for a given atom is the atomic number Z,which tells us the number of electrons in the neutral atom. we start by writing the first potential energy level,then the possible types of orbitals in this level,and then the an odd number and we are down to the last electron in the valence shell.In this course we will seldom be concerned with elements beyond the second row,so we'll keep it simple.the electronic configurations for the nonmetals of the second row are shownbelow.