Which of the following is the correct Lewis electron dot structure for neutral magnesium chloride (MgCl_2)?

• A. Mg^{2+} [ :Cl: ] [ :Cl: ]
• B. Mg [ :Cl: ] [ :Cl: ]
• C. Mg^{2+} [ :Cl: ]^{-} [ :Cl: ]^{-}
• D. Mg [ :Cl: ]^{-} [ :Cl: ]^{-}

Answer: (C)

Verified step by step guidance

1. Step 1: Identify the nature of bonding in magnesium chloride (MgCl_2). Magnesium is a metal and chlorine is a nonmetal, so MgCl_2 is an ionic compound formed by the transfer of electrons from magnesium to chlorine atoms.
2. Step 2: Determine the electron configuration changes. Magnesium (Mg) starts with 2 valence electrons and tends to lose both to achieve a stable noble gas configuration, becoming Mg^{2+}. Each chlorine atom (Cl) needs one electron to complete its octet, so each Cl gains one electron, becoming Cl^{-}.
3. Step 3: Draw the Lewis structure for the ions. Represent Mg as Mg^{2+} with no dots around it because it has lost its valence electrons. Each Cl^{-} should be shown with 8 dots (4 pairs) around the symbol to represent the full octet, and a negative charge to indicate the extra electron.
4. Step 4: Combine the ions to form the neutral compound. Since Mg^{2+} has a +2 charge and each Cl^{-} has a -1 charge, two Cl^{-} ions balance the charge of one Mg^{2+} ion, resulting in a neutral MgCl_2 compound.
5. Step 5: Verify the overall charge and octet completion. Ensure that the Mg ion has no valence electrons (due to loss) and each Cl ion has a complete octet with a negative charge, confirming the correct Lewis electron dot structure is Mg^{2+} [ :Cl: ]^{-} [ :Cl: ]^{-}.