Which of the following best describes the Lewis dot structure for the neutral compound SeO_2?

• A. The selenium atom is bonded to two oxygen atoms with single bonds, and each oxygen has three lone pairs.
• B. The selenium atom is bonded to two oxygen atoms with double bonds, and each oxygen has two lone pairs.
• C. The selenium atom is bonded to one oxygen atom with a double bond and to the other with a single bond; the single-bonded oxygen has three lone pairs.
• D. The selenium atom is bonded to two oxygen atoms with triple bonds, and each oxygen has one lone pair.

Answer: (B)

Verified step by step guidance

1. Step 1: Determine the total number of valence electrons available for the SeO_2 molecule. Selenium (Se) is in group 16 and has 6 valence electrons, and each oxygen (O) atom also has 6 valence electrons. So, total valence electrons = 6 (Se) + 2 × 6 (O) = 18 electrons.
2. Step 2: Draw a skeletal structure with selenium as the central atom bonded to two oxygen atoms. Connect Se to each O with single bonds initially, using 2 electrons per bond, which accounts for 4 electrons.
3. Step 3: Distribute the remaining electrons to satisfy the octet rule for the oxygen atoms first by adding lone pairs. Each oxygen needs 8 electrons total (including bonding electrons). After placing lone pairs, check if the octet rule is satisfied for oxygen and selenium.
4. Step 4: If selenium does not have a complete octet, consider forming double bonds by converting lone pairs on oxygen into bonding pairs between Se and O. This will reduce lone pairs on oxygen and increase bonding electrons, helping selenium reach an octet.
5. Step 5: Confirm the final Lewis structure by counting all electrons to ensure the total matches the valence electrons calculated in Step 1, and verify that all atoms have complete octets (or expanded octet if applicable). The most stable structure will have selenium bonded to two oxygens with double bonds, and each oxygen having two lone pairs.