Question 6.14: Draw the Lewis structures for carbon dioxide, CO2.

STEP 1   Determine the arrangement of atoms. In $CO_{2}$ , the central atom is C because there is only one C atom.

STEP 2   Determine the total number of valence electrons. We use the group numbers to determine the number of valence electrons for each of the atoms in the molecule.

STEP 3   Attach each bonded atom to the central atom with a pair of electrons.

We use four valence electrons to attach the central C atom to two O atoms, which leaves 12 valence electrons.

STEP 4   Use the remaining electrons to complete octets, using multiple bonds if needed. The 12 remaining electrons are placed as six lone pairs of electrons on the outside O atoms. However, this does not complete the octet of the C atom.

To obtain an octet, the C atom must share pairs of electrons from each of the O atoms. When two bonding pairs occur between atoms, it is known as a double bond.