The type of chemical bond between carbon and oxygen atoms in a carbon monoxide CO molecule is a triple bond, specifically consisting of two pi bonds and one sigma bond. This occurs because carbon has 4 valence electrons and oxygen has 6 valence electrons. In order to achieve a stable octet configuration, carbon shares 3 electrons with oxygen, while oxygen shares 3 electrons with carbon. This results in a triple bond, which is a strong bond that holds the carbon and oxygen atoms together in a carbon monoxide molecule.