For Calcium Carbonate, Draw Both the Cation and the Anions as Standalone Ions, Draw the Most Common Lewis Structure and Do Not Draw Alternative Resonance Forms

Calcium carbonate, with the formula CaCO₃, consists of a calcium cation (Ca²⁺) and a carbonate anion (CO₃^2-). Let’s break this down:

Cation and Anions as Standalone Ions

The cation is:

• Ca²⁺ – This indicates that calcium has lost two electrons, resulting in a positive charge.

The anion is:

• CO₃^2- – This represents the carbonate ion. It has a net charge of -2, which comes from the total of valence electrons in the structure.

Lewis Structure of Calcium Carbonate

The most common Lewis structure for calcium carbonate does not depict resonance forms, focusing instead on the simple bonding arrangement. In this structure:

• Calcium is depicted as a single Ca²⁺ ion.
• The carbonate ion is depicted with one carbon atom bonded to three oxygen atoms, where one of the oxygen atoms has a double bond with carbon.

The Lewis structure looks like this:

       O
       ||
    O=C-O-
       |
    O-

In this structure, the carbon (C) atom serves as the central atom, bonded to three oxygen (O) atoms. Two of the oxygen atoms each carry a single bond and a negative charge, while one oxygen is double-bonded to the carbon. This arrangement fulfills the octet rule for carbon and gives the carbonate ion its overall charge balance.