In carbon dioxide (CO2), the correct structure is represented as:
O=C=O
This indicates that the carbon atom is double bonded to each of the oxygen atoms. Carbon, which has 4 valence electrons, can form four bonds, while each oxygen atom, with 6 valence electrons, can form two bonds. In CO2, carbon uses its four valence electrons to form two double bonds with the two oxygen atoms, achieving a stable configuration.