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
Carbon, with four valence electrons, forms covalent bonds to four neighboring carbon atoms arranged toward the corners of a tetrahedron, as shown in the figure below. Each of these sp 3 -hybridized atoms is then bound to four other carbon atoms, which form bonds to four other carbon atoms, and so on.arbon therefore forms covalent bonds with many other elements. 3. Carbon forms strong double and triple bonds with a number of other nonmetals, including N, O, P, and S. Elemental Forms of Carbon: Graphite, Diamond, Coke, and Carbon Black. Carbon occurs as a variety of allotropes.