CHEMISTRY GLOSSARY

gadolinium    →   gadolinij

Gadolinium was discovered by Jean de Marignac (France) in 1880. Named after the mineral gadolinite, named for J. Gadolin, a Finnish chemist and mineralogist. It is soft, ductile, silvery-white metal. Reacts slowly with water and oxygen. Dissolves in acids. Metal ignites and burns readily. Gadolinium is found with other rare earths in gadolinite and monazite sand. Used in steel alloying agents and the manufacture of electronic components.

graphite    →   grafit

Graphite is an allotrope of carbon. The atoms are arranged in layers as a series of flat, hexagonal rings. Graphite is a good conductor of heat and electricity. The layers cleave easily, making graphite useful as a solid lubricant. A process to make pure synthetic graphite was invented by the American chemist Edward Goodrich Acheson (1856–1931). The process consists of heating a mixture of clay (aluminum silicate) and powdered coke (carbon) in an iron bowl. The reaction involves the production of silicon carbide, which loses silicon at 4150 °C to leave graphite.

hafnium    →   hafnij

Hafnium was discovered by Dirk Coster (Denmark) and Georg Karl von Hevesy (Hungary) in 1923. The origin of the name comes from the Latin name Hafnia meaning Copenhagen. It is silvery, ductile metal. Exposed surfaces form oxide film. Resists alkalis and acids (except HF). Toxic. Metal ignites and burns readily. Hafnium is obtained from mineral zircon or baddeleyite. Used in reactor control rods because of its ability to absorb neutrons.

holmium    →   holmij

Holmium was discovered by Per Theodore Cleve (Sweden) in 1879. The origin of the name comes from the Greek word Holmia meaning Stockholm. It is fairly soft, malleable, lustrous, silvery metal. Reacts slowly with oxygen and water. Dissolves in acids. Can react violently with air or halogens. Holmium occurs in gadolinite. Most often from monazite sand. It has very few practical applications; however, it has some unusual magnetic properties that offer some hope for future applications.

indium    →   indij

Indium was discovered by Ferdinand Reich and Hieronymus Theodor Richter (Germany) in 1863. Named after the indicum (colour indigo), the colour it shows in a spectroscope. It is rare, very soft, silver-white metal. Stable in air and water. Dissolves in acids. Metal can ignite and burn. Indium is found in certain zinc ores. Used to coat high speed bearings and as an alloy that lowers the melting point of other metals. Relatively small amounts are used in dental items and in electronic semiconductors.

iron    →   željezo

Iron has been known since ancient times. The origin of the name comes from the Latin word ferrum meaning iron. It is malleable, ductile, silvery-white metal. Exposed surfaces form red-brown oxides. Forms very strong alloys (steel). Ferromagnetic. Metal dust flammable. Fourth most abundant element in the earth’s crust. Iron is obtained from iron ores. Pure metal produced in blast furnaces by layering limestone, coke and iron ore and forcing hot gasses into the bottom. This heats the coke red hot and the iron is reduced from its oxides and liquefied where it flows to the bottom. Iron is the most common metal in human society. More than 90 % of all metal refined in the world is iron. Used in steel and other alloys. It is the chief constituent of hemoglobin which carries oxygen in blood vessels. Its oxides are used in magnetic tapes and disks.

Knudsen burette    →   Knudsenova bireta

Knudsen's automatic bulb-burette, developed by the Danish physicist Martin Knudsen (1871-1949), is designed in a way that even routine field analysis in a boat laboratory would provide highly accurate measurements. The burette is filled with a mixture of silver nitrate from reservoir R, located above the burette, by opening the A valve. When the solution crosses the three-way C valve the A valve is closed preventing further solution flow in to the burette. Any extra solution is caught in the W bowl. Turn the C valve, which marks the zero on the scale, in order to allow atmospheric air to enter the burette. Since most open-ocean samples lie in a relatively small chlorinity range, the burette is designed so that much of its capacity is in the bulb (B). This allows the titration to be quick (by quickly releasing contents from the B area) and reduces the error that occurs from the slow drainage along the inner wall of the burette.

Each millimeter is divided in to twenty parts (double millimeter division of the Knudsen burette) which allows for highly accurate measurements (the scale is read up to a precision of 0.005 mL). From 0 to 16 the burette isn't divided, that usually starts from 16 and goes until 20.5 or 21.5. A single double millimeter on a Knudsen burette scale corresponds to one permille of chloride in the seawater sample. This burette can be used for titration of water from all of the oceans and seas, with the exemptions being areas with very low salinity (e.g. the Baltic Sea) and river estuaries which require the use of normal burettes.

lanthanides    →   lantanoidi

Lanthanides (lanthanons, lanthanoids or rare-earth elements) are a series of fourteen elements in the periodic table, generally considered to range in proton number from cerium to lutetium inclusive. It was convenient to divide these elements into the cerium group or light earth: cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu); and the yttrium group or heavy earths: gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) i lutetium (Lu). The position of lanthanum is somewhat equivocal and, although not itself a lanthanide, it is often included with them for comparative purpose. The lanthanides are sometimes simply called the rare earths. Apart from unstable Pm, the lanthanides are actually not rare. Cerium is the 26. most abundant of all elements, 5 times as abundant as Pb. All are silvery very reactive metals.

lanthanum    →   lantan

Lanthanum was discovered by Carl Gustaf Mosander (Sweden) in 1839. The origin of the name comes from the Greek word lanthanein meaning to lie hidden. It is soft, silvery-white, malleable, ductile metal. Readily tarnishes in air. Reaction with water releases hydrogen gas. Metal ignites and burns readily. Reacts with oxidants. Lanthanum is found with rare earths in monazite and bastnasite. Monazite sand typical contains 25 % lanthanum. It is used in the electrodes of high-intensity, carbon-arc lights. Because it gives glass refractive properties, it is used in expensive camera lenses.

lead    →   olovo

Lead has been known since ancient times. The origin of the name comes from the Latin word plumbum meaning liquid silver. It is very soft, highly malleable and ductile, blue-white shiny metal. Tarnishes in moist air; stable in oxygen and water. Dissolves in nitric acid. Compounds toxic by inhalation or ingestion. Danger of cumulative effects. Lead is found most often in ores called galena or lead sulfide (PbS). Used in solder, shielding against radiation and in batteries.