Multiple Choice
Which of the following statements correctly describes the Lewis dot structure of the formate ion, CHO2-?
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11. Bonding & Molecular Structure
Lewis Dot Structures: Ions
Multiple Choice
Which of the following is the best Lewis dot structure for the ion SeO4^{2-}?
A
Se atom in the center, bonded to four O atoms with single bonds; each O atom has three lone pairs; Se has one lone pair; overall charge is 2-.
B
Se atom in the center, bonded to four O atoms with double bonds; each O atom has two lone pairs; Se has no lone pairs; overall charge is 2-.
C
Se atom in the center, bonded to four O atoms with single bonds; each O atom has three lone pairs; Se has no lone pairs; overall charge is 2-.
D
Se atom in the center, bonded to two O atoms with double bonds and two O atoms with single bonds; each O atom has appropriate lone pairs; Se has no lone pairs; overall charge is 2-.
Verified step by step guidance1
Step 1: Determine the total number of valence electrons available for the SeO4^{2-} ion. Selenium (Se) has 6 valence electrons, each oxygen (O) has 6 valence electrons, and the 2- charge adds 2 extra electrons. Calculate the total as: \(6 + 4 \times 6 + 2\).
Step 2: Draw a skeletal structure with Se as the central atom bonded to four oxygen atoms. Connect each oxygen to Se with a single bond initially, using 2 electrons per bond.
Step 3: Distribute the remaining electrons as lone pairs to complete the octets of the oxygen atoms first, since oxygen typically follows the octet rule strictly.
Step 4: Check the formal charges on each atom by using the formula: \(\text{Formal charge} = \text{Valence electrons} - (\text{Nonbonding electrons} + \frac{1}{2} \times \text{Bonding electrons})\). Adjust bonding (single or double bonds) to minimize formal charges, especially on oxygen atoms.
Step 5: Evaluate the resonance structures and overall charge. The best Lewis structure will have the lowest formal charges on atoms, full octets on oxygens, and an overall charge of 2-. Confirm if Se has any lone pairs and the bonding pattern that satisfies these conditions.
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