In carbon dioxide (CO2), there are two oxygen atoms for each carbon atom. Each oxygen atom forms a double bond with carbon, so the molecule contains two sets of double bonds. Two sets of double bonds means that the total number of electrons being shared in the molecule is two. four. six. eight. In carbon dioxide (CO2), there are two oxygen atoms for each carbon atom. Each oxygen atom forms a double bond with carbon, so the molecule contains two sets of double bonds. Two sets of double bonds means that the total number of electrons being shared in the molecule is two. four. six. eight.