Which of the following statements correctly describes the Lewis dot structure of the bicarbonate ion (HCO3^-)?

• A. It contains one hydrogen atom bonded to an oxygen atom, with three resonance structures involving the placement of double bonds among the oxygens.
• B. It contains a central carbon atom bonded to three hydrogen atoms and one oxygen atom, with no resonance structures.
• C. It contains a central carbon atom bonded to two hydrogen atoms and two oxygen atoms, with no formal charges.
• D. It contains a central oxygen atom bonded to three carbon atoms and one hydrogen atom, with two resonance structures.

Answer: (A)

Verified step by step guidance

1. Identify the molecular formula and charge of the bicarbonate ion, HCO3⁻, which consists of one hydrogen (H), one carbon (C), and three oxygen (O) atoms, with an overall negative charge of -1.
2. Determine the central atom in the Lewis structure. Since carbon typically forms four bonds and is less electronegative than oxygen, carbon will be the central atom bonded to the other atoms.
3. Arrange the atoms with carbon in the center bonded to three oxygen atoms, and one of these oxygens is also bonded to the hydrogen atom, forming an O-H bond.
4. Calculate the total number of valence electrons: carbon has 4, each oxygen has 6 (total 18 for three oxygens), hydrogen has 1, and add 1 extra electron for the negative charge, summing to 24 valence electrons.
5. Draw the Lewis structure with single bonds initially, then distribute the remaining electrons to satisfy the octet rule for oxygen and carbon. Recognize that resonance structures occur because the double bond between carbon and oxygen can be placed in different positions among the three oxygens, while the hydrogen remains bonded to one oxygen.