assuming that your periodic table has eighteen columns, you should highlight the four elements in the third column from the left of the table.
explanation
neutral atoms of elements after calcium contain d electrons. the energy of d orbitals of a particular main shell lies between the energy of the s and p orbitals of the next main shell. for example, electrons in the
have energy higher than those in the
orbital while lower than those of the
orbital.
by the aufbau principle, electrons fill orbitals one at a time, starting from those of the lowest energy. the
orbital is therefore filled right after
orbitals and before
orbitals.
potassium has electron configuration
and calcium
. the s orbital of a main shell holds a maximum of two electrons. the next element would thus have the electron configuration
and satisfy the requirements.
a neutral atom of the element contains three electrons on top of the most recent noble gas element. it should thus be placed in the third column of the periodic table. both scandium and yttrium would satisfy the conditions. an aufbau diagram indicates that the 4f orbital is filled before the 5d. however, it appears that exceptions exists for both lanthanum and actinium. neutral atoms of the two d-block elements also demonstrate the
and should be highlighted as well.