To determine which two elements would bond together based on their ionic charges, we need to look at their group numbers and the typical charges of the ions they form:
- Potassium (K) is in Group IA, which typically forms a +1 charge as a cation (K⁺).
- Calcium (Ca) is in Group IIA, which typically forms a +2 charge as a cation (Ca²⁺).
- Iodine (I) is in Group VIIA, which typically forms a -1 charge as an anion (I⁻).
- Neon (Ne) is in Group VIIIA and is a noble gas that typically does not form bonds.
Based on this information, the only combination that involves a cation and an anion is potassium (K⁺) and iodine (I⁻).
Therefore, the correct response is:
Potassium and iodine.