Question

Which statement describes the trend in first ionization energy for elements on the periodic table?

Answer 1

First ionisation down a group = Decreases, due to the shielding effect of the increased number of shells, so the electron is easier to remove as there isn't as much of an attraction between the nucleus and the outer electrons.

First ionisation across a period = Increases, due to the increase of protons and electrons but no increase of shells making the attraction between the protons and electrons stronger as more are being added, but no shells are stopping them from being attracted to each other.