Question

Compare and contrast the second ionization energies of K and Ca?

Please address the proton to electron ratio

Answer 1

The energies can be easily looked up. The question is, "What makes them so different?" The answer is in the stability of the resulting electron shell.

Explanation:

The "second ionization" means that the first valence electron has already been removed. For Ca this means that it's valence shell is still "imbalanced" - it really wants to lose another electron to get to a more stable electronic configuration (`Ca^(2+)`).

On the other hand, K has reached a stable configuration after the first electron loss (`K^(1+)`). Removing the next one requires overcoming not only the charge/attraction difference of the protons to the remaining electrons - as it does with Ca as well - but creating a less stable electronic configuration for the atom.

Ca second ionization energy: `1145.4 kJ/"mol"`
K second ionization energy: `3052 kJ/"mol"`