Which Lewis structure below correctly represents the compound formed between magnesium and sulfur?

• A. Mg with no dots and S with eight dots, with Mg and S connected by brackets and charges: [Mg]^{2+} [S]^{2-}
• B. Mg with one dot and S with seven dots, connected by a single line
• C. Mg with two dots and S with six dots, connected by a single line
• D. Mg and S each with eight dots, connected by a double line

Answer: (A)

Verified step by step guidance

1. Step 1: Identify the types of elements involved and their typical ionic charges. Magnesium (Mg) is a metal that commonly forms a +2 cation (Mg^{2+}), and sulfur (S) is a nonmetal that commonly forms a -2 anion (S^{2-}).
2. Step 2: Understand that the compound formed between Mg and S is ionic, meaning electrons are transferred from Mg to S rather than shared. This results in Mg losing two electrons and S gaining two electrons.
3. Step 3: Recognize that in the Lewis structure for ionic compounds, the metal cation (Mg^{2+}) is represented without any dots (since it has lost its valence electrons), and the nonmetal anion (S^{2-}) is represented with a full octet of eight dots around it, indicating it has gained electrons.
4. Step 4: Note that the ions are shown in brackets with their respective charges to indicate the ionic nature of the compound, for example, [Mg]^{2+} and [S]^{2-}. There are no lines (bonds) between them because ionic bonds are electrostatic attractions, not shared electron pairs.
5. Step 5: Compare this understanding to the given options and select the Lewis structure that shows Mg with no dots and a 2+ charge, S with eight dots and a 2- charge, both enclosed in brackets, representing the ionic compound MgS correctly.