To determine which elements in the list would bond together based on their ionic charges, we need to consider the typical charges of the elements based on their group numbers in the periodic table:
- Potassium (K) is in Group IA (1A) and typically has a +1 charge when it forms an ion (K⁺).
- Calcium (Ca) is in Group IIA (2A) and typically has a +2 charge when it forms an ion (Ca²⁺).
- Iodine (I) is in Group VIIA (7A) and typically has a -1 charge when it forms an ion (I⁻).
- Neon (Ne) is a noble gas in Group VIIIA (8A) and does not typically form bonds because it has a full valence shell and is generally unreactive.
When considering the pairs:
- Potassium (K) and Iodine (I): K⁺ (charge +1) and I⁻ (charge -1) can bond together to form potassium iodide (KI).
- Potassium and Neon: Neon does not bond as it is inert.
- Calcium and Potassium: Both are metals and do not typically bond with each other.
- Calcium and Neon: Neon does not bond as it is inert.
Thus, the correct answer is:
Potassium and Iodine (potassium and iodine).