The second ionization energy is always larger than the first ionization energy. The chemical properties of elements are periodic functions of their atomic number. Electron affinity becomes more negative as you go up a family or group of elements. Once an electron has been removed from a neutral atom, the second electron is usually easier to remove. First ionization is the minimum amount of energy required to remove the most loosely held electron from a gaseous atom.
Metals have lower ionization energies than nonmetals.
I only 52. The total number of electrons that can occupy an atomic orbital is 1. The Heisenberg Uncertainty Principle. The Pauli Exclusion Principle. Once an electron has been removed from a neutral atom, the second electron is harder to remove.