Chapter 7 - Periodic Properties of the Elements - Exercises - Page 292: 7.41a

The smaller the size of the atom is, the larger the first ionization energy would be.

The size of an atom depends on the strength of attraction from the nucleus to the outermost electrons. The stronger the attraction and the less the screening effect are, the closer the outermost electrons would be pulled closer to the nucleus, making the atom size smaller and smaller. The first ionization energy also depends on the strength of attraction from the nucleus to the outermost electrons. The stronger the attraction and the less the screening effect are, the harder to remove an electron is, making the first ionization energy larger and larger. As a result, there is a relationship between the atom size and the first ionization energy. The smaller the size of the atom is, the more the outermost electrons are attracted to the nucleus, and therefore, the larger the first ionization energy must be.