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
Concept 4.2 Carbon atoms can form diverse molecules by bonding to four other atoms. With a total of 6 electrons, a carbon atom has 2 in the first electron shell and 4 in the second shell. Carbon has little tendency to form ionic bonds by losing or gaining 4 electrons to complete its valence shell.oncept 4.2 Carbon atoms can form diverse molecules by bonding to four other atoms. With a total of 6 electrons, a carbon atom has 2 in the first electron shell and 4 in the second shell. Carbon has little tendency to form ionic bonds by losing or gaining 4 electrons to complete its valence shell.