The molecular geometry of carbon dioxide CO2 is linear, and the bond angle is 180 degrees. This geometry is determined using quantum chemistry principles, specifically through the application of molecular orbital theory and valence shell electron pair repulsion VSEPR theory.Molecular orbital theory involves the combination of atomic orbitals to form molecular orbitals, which describe the electron distribution in a molecule. In CO2, the central carbon atom has four valence electrons, while each oxygen atom has six valence electrons. The carbon atom forms two double bonds with the oxygen atoms, sharing two pairs of electrons with each oxygen atom. This results in a total of four electron pairs involved in bonding.According to VSEPR theory, electron pairs around a central atom repel each other and arrange themselves to minimize repulsion. In the case of CO2, there are two electron pairs involved in bonding double bonds and no lone pairs on the central carbon atom. These electron pairs repel each other and arrange themselves as far apart as possible, resulting in a linear molecular geometry with a bond angle of 180 degrees.Quantum chemistry calculations, such as those based on the Schrödinger equation or density functional theory DFT , can also be used to determine the molecular geometry and bond angles of CO2. These calculations involve solving the electronic wavefunction of the molecule and determining the most stable geometry that minimizes the total energy of the system. In the case of CO2, these calculations confirm the linear geometry and 180-degree bond angle predicted by VSEPR theory.