 Solution

The central carbon in carbon dioxide has two bonding directions and no lone pair, whereas the central oxygen in ozone has two bonding directions and one lone pair. In the VSEPR model, carbon dioxide therefore has a linear arrangement; ozone has an approximately trigonal-planar electron-domain arrangement but a bent atomic skeleton. Multiple bonding occupies one direction for this geometrical count. The extra central-oxygen lone pair, rather than a different number of atomic nuclei, creates the difference.