why the third ionization energy of Calcium would be much higher than the 1st and 2nd ionization energy?

The more penetrating the location of orbital electrons, the more difficult it is to remove and the higher the ionization energy.

Ionization energy is the energy required to remove an electron from an atom. Valence or outer most shell electrons are very easy to remove because they are in the outer most shell.

The nuclear pull of the nucleus of an atom is very great towards the inner orbital electrons but on the outermost shell electrons, it is quite low.

It takes more energy to remove the inner most electrons because they are more tightly held by the nucleus.

The first ionization energy is the energy required to remove the most outermost electron in an atom.