Based on their positions in the periodic table, predict which atom of the following pairs will have the smaller first ionization energy: (a) Br, Kr (b) C, Ca (c) Li, Rb (d) S, Ge (e) Al, B.

Ionization energy is the energy required to remove an electron from a gaseous atom or ion. It is a key concept in understanding how easily an atom can lose an electron, which is influenced by factors such as atomic size and effective nuclear charge. Generally, ionization energy increases across a period and decreases down a group in the periodic table.

Periodic trends refer to the predictable patterns observed in the properties of elements as you move across or down the periodic table. For ionization energy, elements on the right side of the table tend to have higher ionization energies than those on the left, while elements higher up in a group have higher ionization energies than those lower down. Understanding these trends helps in predicting the behavior of elements.

Atomic structure involves the arrangement of protons, neutrons, and electrons in an atom. The number of protons (atomic number) determines the element's identity, while the arrangement of electrons affects its chemical properties, including ionization energy. Elements like sulfur (S) and germanium (Ge) have different atomic structures, influencing their respective ionization energies.