CO2 is a linear triatomic molecule. Each C = O bond is polar because O more electronegative than C, so O is the partial negative end of the bond dipole.
The Lewis structure of CO2 is
The double bond behaves just like a single bond for purposes of predicting molecular shape.This compound has two groups of electrons around the carbon. According to VSEPR theory, the two sets of electrons will orient themselves 180o apart, on opposite sides of the carbon atom, minimizing electron repulsion. Therefore the molecular structure of CO2 is linear.
Double and triple bonds involve more electron pairs than single bonds, but this has little effect on the overall molecular shape. All of the electron pairs in a multiple bond are shared between the same two nuclei and therefore occupy the same region of space.
All electron pairs in a multiple bond count as one bond and contribute to molecular geometry the same as a single bond does. The carbon atom in CO2 has no lone pairs and participates in two double bonds. Each double bond counts as one for the purpose of predicting geometry so the structure of CO2 is linear.
In CO2 molecule the carbon atom has two effective pairs that will be arranged at an angle of 180 degree. We therefore need a pair of atomic oriented in opposite directions. This requires hybridization, since neither sp3 nor sp2 hybrid orbitals will fit in this case.
To obtain arranged at 180 degrees requires sp hybridization, involving one s orbital and one p orbital as shown below.
In the CO2 molecule each oxygen atom has three effective pairs around it, requiring a trigonal planar arrangement of the pairs. Since a trigonal set of hybrid orbitals requires sp2 hybridization, each oxygen atom is sp2 hybridized, One p orbital on each oxygen is unchanged and is used for the a bond with the carbon atom.
The orbitals used to form bonds in carbon dioxide is shown below.
The molecular geometry of CO2 is linear. Each C=O bond is polar, but these bond dipole point in opposite directions (180o), so they cancel making CO2 a non polar molecule.
|Number of bonds
||Type of hybrid orbital
Angle between bonded atoms