The best Lewis structure for a carbonate ion, CO
, should show \ single bond(s), \ double bond(s), and \ lone pair(s) of electrons on the \ central atom. \ Fill in the blanks using number, eg. 0, 1, 2, 3, etc.
The Correct Answer and Explanation is:
The best Lewis structure for a carbonate ion, CO₃²⁻, should show 1 single bond(s), 2 double bond(s), and 0 lone pair(s) of electrons on the central atom.
Explanation:
- Valence Electrons:
The carbonate ion (CO₃²⁻) consists of carbon (C) and oxygen (O). Carbon is in Group 14 of the periodic table, so it has 4 valence electrons. Each oxygen atom (Group 16) has 6 valence electrons, and there are three oxygen atoms in the ion. The ion carries a 2- charge, so we add 2 extra electrons. The total number of valence electrons = (4 from C)+(3×6 from O)+2 (charge)=24 valence electrons.(4 \text{ from C}) + (3 \times 6 \text{ from O}) + 2 \text{ (charge)} = 24 \text{ valence electrons}.(4 from C)+(3×6 from O)+2 (charge)=24 valence electrons. - Bonding and Structure:
The central atom is carbon, which forms bonds with each of the three oxygen atoms. Since carbon only needs 4 valence electrons to complete its octet, it will form one double bond with one oxygen and two single bonds with the other two oxygen atoms. This creates a structure where carbon has a formal charge of 0 (ideal situation). - Resonance:
The carbonate ion has resonance, meaning that the bonds between carbon and oxygen are not fixed. The actual structure is a hybrid, with the bond order being an average of one and a third. Therefore, each of the C–O bonds is considered to have partial double-bond character. - Electron Pairs on Central Atom:
In the best Lewis structure, carbon does not have any lone pairs. It uses all its valence electrons for bonding with oxygen atoms.
Thus, the correct Lewis structure has 1 double bond, 2 single bonds, and no lone pairs on the central carbon atom.
