Which electron-dot (Lewis) structure correctly represents the neutral compound calcium oxide?

• A. Ca^{2+} :O^{2-}:
• B. Ca^{+} :O^{-}:
• C. Ca :O:
• D. :Ca:O:

Answer: (A)

Verified step by step guidance

1. Step 1: Identify the elements involved and their typical charges. Calcium (Ca) is an alkaline earth metal that commonly forms a +2 cation (Ca^{2+}), and oxygen (O) is a nonmetal that commonly forms a -2 anion (O^{2-}) in ionic compounds.
2. Step 2: Understand that calcium oxide (CaO) is an ionic compound formed by the transfer of electrons from calcium to oxygen, resulting in Ca^{2+} and O^{2-} ions.
3. Step 3: Draw the Lewis electron-dot structure by showing calcium with no dots (since it loses its two valence electrons) and oxygen with eight dots (representing a full octet) and a 2- charge to indicate it has gained two electrons.
4. Step 4: Represent the charges explicitly: write Ca^{2+} without dots and O^{2-} with eight dots around it, indicating the full octet and the negative charge.
5. Step 5: Confirm that the structure reflects the neutral compound overall, with the +2 charge on calcium balancing the -2 charge on oxygen, resulting in a neutral ionic compound CaO.