(a) Which has the smaller fourth ionization energy, Sn or Sb?

Ionization energy is the energy required to remove an electron from an atom or ion in its gaseous state. It is a key factor in determining an element's reactivity and is influenced by the atomic size and the effective nuclear charge. Generally, ionization energy increases across a period and decreases down a group in the periodic table.

The periodic table exhibits specific trends in properties such as ionization energy, electronegativity, and atomic radius. As you move from left to right across a period, ionization energy tends to increase due to the increasing nuclear charge. Conversely, as you move down a group, ionization energy decreases because of the increased distance between the nucleus and the outermost electrons, which are more shielded by inner electrons.

Tin (Sn) and antimony (Sb) are elements in groups 14 and 15 of the periodic table, respectively. The fourth ionization energy refers to the energy needed to remove the fourth electron from an atom. Understanding the electronic configurations and the stability of the resulting ions after successive ionizations is crucial for predicting which element will have a lower fourth ionization energy.