Carbon dioxide CO2 is a linear molecule with a central carbon atom double-bonded to two oxygen atoms. According to quantum mechanics principles, the molecular structure and geometry of CO2 can be explained using molecular orbital theory and valence shell electron pair repulsion VSEPR theory.Molecular Orbital Theory:In CO2, the central carbon atom has four valence electrons, and each oxygen atom has six valence electrons. The carbon atom forms two double bonds with the oxygen atoms, which means it shares two pairs of electrons with each oxygen atom. The molecular orbitals of CO2 can be described as a combination of atomic orbitals from the carbon and oxygen atoms. The bonding molecular orbitals are formed by the overlap of the carbon 2s and 2p orbitals with the oxygen 2s and 2p orbitals, while the antibonding molecular orbitals result from the out-of-phase combination of these atomic orbitals.VSEPR Theory:The VSEPR theory predicts the geometry of a molecule based on the repulsion between electron pairs in the valence shell of the central atom. In CO2, the central carbon atom has two electron domains two double bonds with oxygen atoms . The electron domains will arrange themselves to minimize repulsion, resulting in a linear geometry with a bond angle of 180 degrees between the oxygen atoms.In summary, according to quantum mechanics principles, the molecular structure and geometry of carbon dioxide CO2 is a linear molecule with a central carbon atom double-bonded to two oxygen atoms, and a bond angle of 180 degrees between the oxygen atoms.