Answer:
Energy required to remove an electron from the atom.
Explanation:
Energy required to remove an electron from an atom describe ionization energy because in chemistry, ionization energy in is the amount of energy needed to remove electrons from the atoms or ions of chemical species.
Ionization energy increases as we move across the period of elements in the group and this is because electrons are bond tighter by high effective nuclear charge and ionization energy of elements increases down the group because electrons are bond together in lower energy orbitals.
