Which of the following best describes the Lewis dot structure for neutral magnesium hydride (MgH_2)?

• A. Mg atom with a double bond to one H atom and a single bond to another H atom.
• B. Mg atom with two single bonds to two H atoms; each H atom has one lone pair.
• C. Mg atom with two single bonds to two H atoms; Mg has no lone pairs.
• D. Mg atom with two lone pairs and no bonds to H atoms.

Answer: (C)

Verified step by step guidance

1. Recall that a Lewis dot structure represents the valence electrons of atoms as dots and bonds as lines between atoms, showing how atoms share or transfer electrons to achieve stable electron configurations.
2. Identify the valence electrons for magnesium (Mg) and hydrogen (H). Magnesium is in group 2, so it has 2 valence electrons, and each hydrogen has 1 valence electron.
3. Consider the typical bonding behavior: hydrogen usually forms one single bond to complete its duet (2 electrons), and magnesium tends to lose its two valence electrons to achieve a stable electron configuration, often forming ionic or covalent bonds accordingly.
4. Construct the Lewis structure by connecting the Mg atom to two H atoms with single bonds, since Mg can share its two valence electrons with two hydrogens, each forming one bond. This satisfies the octet rule for Mg and the duet rule for H.
5. Verify that in this structure, Mg has no lone pairs (all its valence electrons are involved in bonding), and each H atom has no lone pairs (each has a single bond), which matches the description: 'Mg atom with two single bonds to two H atoms; Mg has no lone pairs.'