Each element on the periodic table belongs to a category of metals, non-metals or metalloids. Metals are the most common type and are defined by certain chemical and physical properties. Metals can be identified by examining their chemical properties. They have positive valences, meaning they donate electrons to the atoms they bond with. By giving up negative electrons, metals form cations. (BrainPop) When metals form cations, they are able to oxidize, making them prone to corrosion when exposed to moisture. Corrosion is the deterioration of materials resulting from a chemical reaction. The most often mentioned corrosion phenomenon is the rusting process. Rust is harmful because it negatively affects the physical properties of metals. A corroded piece of iron is not durable, malleable and will no longer ensure its functionality. Most metals rust, but the rate at which they corrode is different. Metals like aluminum seem to resist corrosion, but iron corrodes quickly. (Nimmo, Bill. PDF) Iron alloys such as steel rust when they come into contact with oxygen and water. Oxygen and water are necessary for rust to occur, and when both come into contact with iron, an oxidation reaction occurs to form rust. The term “oxidation” refers to the addition of oxygen to a substance. The element whose atoms bond to the oxygen atoms is said to be oxidized. For example: magnesium + oxygen → magnesium oxide2Mg + O2→ 2MgOIn this case, the magnesium is said to be oxidized because it has bonded with oxygen to form magnesium oxide. (BBC News. BBC) “Reduction,” on the other hand, is the loss of oxygen in a substance. Many metals can be extracted from their ores by reduction methods. For example, copper oxide may be the medium of the paper. Iron rusting, or purchasing iron alloys that do not corrode, would have a better impact on society environmentally, economically and socially. Works CitedBBC News. BBC and Web. May 22, 2014. “Corrosion and environment”. Lehigh. Np, and Web. May 22, 2014. “Metals.” BrainPOP. Np, and Web. May 21, 2014. .Nimmo, Bill and Gareth Hinds. Beginner's Guide to Corrosion. Np: np, nd PDF. “Return to RideAccidents.com.” RideAccidents.com. Np, and Web. May 23, 2014. “Water Main Repair Costs.” Home advisor. Np, and Web. May 23 2014. .