Which Element in Each Pair Has the Larger Ionization Energy

Which element in each pair has the larger first ionization energy? Sodium has the larger first ionization energy and in the second pair, Phosphorus has the largest first ionization energy.

What makes an element have a higher ionization energy?

The ionization energy of an element increases as one moves across a period in the periodic table because the electrons are held tighter by the higher effective nuclear charge.

How do you know which element has a higher second ionization energy?

The magnitude of the second ionization energy will thus depend on how far away from the nucleus the electron that must be removed is. Electrons located closer to the nucleus will require more energy to be removed. Likewise, electrons located further away from the nucleus will require less energy to remove.