Final answer:
Ionic bond formation is influenced by ionization energy and electron affinity. Ionization energy increases across a period and decreases down a group in the periodic table due to changes in nuclear charge and electron distance from the nucleus.
Step-by-step explanation:
There are two main factors that affect ionic bond formation: ionization energy and electron affinity. Ionization energy is the energy required to remove an electron from an atom, while electron affinity is the energy change when an atom gains an electron.
The trend of ionization energy in the periodic table can be described as follows: ionization energy generally increases across a period (from left to right) and decreases down a group (from top to bottom). This trend occurs due to the increasing nuclear charge across a period, which holds the electrons more tightly and requires more energy to remove them. Conversely, as one moves down a group, the outer electrons are further from the nucleus, thus they're more easily removed due to less nuclear attraction.