Bakar

The metal

Copper is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orange color. Copper is one of the few native metals, meaning metals that occur naturally in a directly usable, unalloyed metallic form.

Copper does not react with water, but it does slowly react with atmospheric oxygen to form a layer of brown-black copper oxide. A green layer of verdigris (copper carbonate) can often be seen on old copper structures, such as the roofing of many older buildings.

The smell of copper

The pungent scent of a handful of pocket change is similar to the smells of a sweat-covered dumbbell or of water emerging from an old metal pipe. The odor molecules come not from a penny or from pipes but from metal-free chemicals released when organic substances like sweat interact with the metallic objects.

Copper has a similar effect to iron, accounting for the metallic smell created by handling coins made of copper alloys. Rapid reactions between iron or copper and oils on the skin produce aldehydes and ketones, which often have strong and distinctive smells.

1-Octen-3-one, also known as octeneone or amyl vinyl ketone, is the odorant responsible for the typical metallic smell of metals such as coins and of blood coming into contact with skin. 1-Octen-3-one (CAS 4312-99-6) has the formula C₈H₁₄O and a molecular weight of 126.20.

Uses

The major applications of copper are electrical wire (60%), roofing and plumbing (20%), and industrial machinery (15%). Copper is used mostly as a pure metal, but when greater hardness is required, it is put into such alloys as brass and bronze. Cupronickel, an alloy of copper, is used to make marine hardware and coins.

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