CHEMISTRY GLOSSARY

bismuth    →   bizmut

Bismuth was discovered by Claude Geoffroy (France) in 1753. The origin of the name comes from the German words Weisse Masse meaning white mass; now spelled wismut and bisemutum. It is hard, brittle, steel-grey metal with a pink tint. Stable in oxygen and water. Dissolves in concentrated nitric acid. Bismuth can be found free in nature and in minerals like bismuthine (Bi₂S₃) and in bismuth ochre (Bi₂O₃) Main use is in pharmaceuticals and low melting point alloys used as fuses.

brass    →   mjed

Brasses are alloys of copper and zinc (generally 5 % to 40 %). Brass has been known to man since prehistoric times, long before zinc itself was discovered. It was produced by melting copper together with calamine, a zinc ore. Its ductility reaches a maximum with about 30 % zinc and its tensile strength with 45 % although this property varies greatly with the mechanical and heat treatment of the alloy. Typical applications included gears, plumbing ware fittings, adapters, valves and screw machine products. The French horn is a valved brass wind instrument.

Brass may contain small amounts of other alloying elements, such as aluminum, lead, tin, or nickel. Lead can be added as an alloying element resulting in a brass that can be rapidly machined and produces minimal tool wear. Additions of aluminium, iron and manganese to brass improve strength, whilst silicon additions improve wear resistance. Brass containing tin (< 2 % ) is less liable to corrosion in seawater; it is sometimes called naval brass and is used in naval construction.

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.

capacitor    →   kondenzator

Capacitor is a device that stores electric charges. The symbol for a capacitor in electric circuit schemes is —| |—.

carbon    →   ugljik

Carbon has been known since ancient times. The origin of the name comes from the Latin word carbo meaning charcoal. Graphite form of carbon is a black, odourless, slippery solid. Graphite sublimes at 3825 °C. Diamond form is a clear or colored; an extremely hard solid. C60 is Buckminsterfullerine. Carbon black burns readily with oxidants. Carbon is made by burning organic compounds with insufficient oxygen. There are close to ten million known carbon compounds, many thousands of which are vital to organic and life processes. Radiocarbon dating uses the carbon-14 isotope to date old objects.

Donnan potential    →   Donnanov potencijal

Donnan potential is the electrical potential difference between two solutions separated by an ion-exchange membrane in the absence of any current flowing through the membrane

electromagnetic wave    →   elektromagnetski val

All matter absorbs and emits radiation covering a broad band of frequencies and wavelengths. Thus electromagnetic radiation has the velocity of light (2.998×10⁸ ms^-1) and arises from the vibrating electric charges in atoms and bonds. The range of wavelengths, also known as the electromagnetic spectrum, is shown below:

cobalt    →   kobalt

Cobalt was discovered by Georg Brandt (Germany) in 1735. The origin of the name comes from the German word kobald meaning goblin or evil spirit. It is hard, ductile, lustrous bluish-grey metal. Surfaces stable in air. Reacts over time with dilute acids. It has remarkable magnetic properties. Cobalt occurs in compounds with arsenic and sulfur as in cobaltine (CoAsS) and linneite (Co₃S₄). Pure cobalt is obtained as a by-product of refining nickel, copper and iron. Used in many hard alloys; for magnets, ceramics and special glasses. Radioactive cobalt-60 is used in cancer therapy.

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.

electrostatics    →   elektrostatika

Electrostatics study of electric charges at rest.