CHEMISTRY GLOSSARY

bronze    →   bronca

Bronze is an alloy made primarily of copper and tin. It may contain as much as 25 % tin. Bronzes with 10 % or more tin are harder, stronger, and resistant to corrosion. As bronze weathers, a brown or green film forms on the surface. This film inhibits corrosion. Silicon or aluminium is often added to bronze to improve resistance to corrosion. Phosphorus, lead, zinc, and other metals may be added for special purposes. The alloy is hard and easily cast and is extensively used in bearings, valves and other machine parts.

Bronze was one of the first alloys developed by ancient metal workers. The Bronze Age occurred in Europe around 2200 to 700 BC. Bronze was used for weapons such as spearheads, swords, and knives. Since ancient times, bronze has been the most popular metal for casting statues and other art objects.

The term bronze has been adopted commercially for many copper-rich alloys that contain little or no tin but are similar in colour to bronze, including aluminium bronze, manganese bronze, and silicon bronze. Aluminium bronze is used to make tools and, because it will not spark when struck. Manganese bronze is actually a brass that contains manganese. It is often used to make ship propellers because it is strong and resists corrosion by sea water.

copper    →   bakar

Copper has been known since ancient times. The origin of the name comes from the Latin word cuprum meaning the island of Cyprus famed for its copper mines. It is malleable, ductile, reddish-brown metal. Resistant to air and water. Exposed surfaces form greenish carbonate film. Pure copper occurs rarely in nature. Usually found in sulfides as in chalcopyrite (CuFeS₂), coveline (CuS), chalcosine (Cu₂S) or oxides like cuprite (Cu₂O). Most often used as an electrical conductor. Also used in the manufacture of water pipes. Its alloys are used in jewellery and for coins.

tin    →   kositar

Tin has been known since ancient times. The origin of the name comes from the Latin word stannum meaning tin. It is silvery-white, soft, malleable and ductile metal. Exposed surfaces form oxide film. Resists oxygen and water. Dissolves in acids and bases. Organic tin compounds may be highly toxic. Tin is principally found in the ore cassiterite (SnO₂) and stannine (Cu₂FeSnS₄). Used as a coating for steel cans since it is non-toxic and non-corrosive. Also in solder (33 %Sn:67 %Pb), bronze (20 %Sn:80 %Cu) and pewter. Stannous fluoride (SnF₂), a compound of tin and fluorine is used in some toothpaste.