Which Lewis electron-dot diagram correctly represents calcium oxide (CaO)?

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

Answer: (D)

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-}).
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: Recognize that the Lewis electron-dot diagram for Ca^{2+} will show no valence electrons around calcium because it has lost two electrons, while the O^{2-} ion will have a full octet represented by eight dots around the oxygen symbol.
4. Step 4: Compare the given options to see which correctly shows calcium as Ca^{2+} (no dots) and oxygen as O^{2-} with eight dots (representing the full octet) and the appropriate charge.
5. Step 5: Conclude that the correct Lewis electron-dot diagram for calcium oxide is the one that shows Ca^{2+} and [O]^{2-}, where calcium has no dots and oxygen has a full octet with a 2- charge.