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
Hydrocarbon Double Bond. The way to tell is to count the number of carbons and the number of hydrogens attached to each. Remember that carbon is tetravalent. If it has a separate bond with each other element, there would be no double bonds. So, C3H8 would NOT have a double bond. Imagine 3 carbons in a row. The C on the left hand side has one bond to the next carbon, and three others - in this case, bonds to hydrogen. The middle carbon has a bond to the C on its left and a bond to the C on its right. So, it could bond to 2 hydrogens. The C on the left hand side has one bond to the C in the middle, and three bonds to hydrogen.