The Prefix is Otterbox's least expensive iPhone case. The durable silicone, polycarbonate skeleton build of the OtterBox Prefix is thicker than the Commuter and Reflex, but also the least protective. The Prefix is a one-piece case, meaning that it does not snap in place like the Reflex .
carbon is considered tetravalent because it has four valence electrons the valence electrons are in the outermost shell of the atom and allows carbon to form four bonds to other atoms
Therefore a Carbon atom can instead share each of its electrons with four separate Hydrogen atoms. This completes the valence shells for four Hydrogen atoms and one Carbon atom. In this example, one pair of electrons is shared between two atoms. The covalent bonds shown below are all called single covalent bonds. As one might surmise, there are a variety of ways of arranging electrons in covalent bonds.