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
Other thsn extreme cases, chemical bonds exist as some combination of ion and covalent character. Carbon form bonds that are very covalent. Since carbon never exists in an ionic state, there's no answer to the quesion what is the charge of a carbon ion. Not even the most electronegative atom in existence (flourine) can compel carbon to form an ion. You just end up with tetrafluoromethane, which is still sufficiently covalently bonded.