CHEMISTRY GLOSSARY
allotrope → alotrop
Allotropes are the elements which exist in two or more different forms in the same physical state. Allotropes generally differ in physical properties and may also differ in chemical activity.
Diamond, graphite and fullerenes are three allotropes of the element carbon. Graphite is a soft, black, slippery substance; by contrast, diamond is one of the hardest substances known. The different properties of the allotropes arise from their chemical structures. Diamonds typically crystallize in the cubic crystal system and consist of tetrahedrally bonded carbon atoms. Graphite crystallizes in the hexagonal system. In the fullerenes, the carbon atoms taking the form of a hollow sphere, ellipsoid, or tube.
In some cases, the allotropes are stable over a temperature range, with a definite transition point at which one changes into the other. For instance, tin has two allotropes: white (metallic) tin stable above 13.2 °C and grey (nonmetallic) tin stable below 13.2 °C.
The term allotropes may also be used to refer to the molecular forms of an element. Ozone is a chemically active triatomic allotrope of the element oxygen.
allotropic modification → alotropska modifikacija
Different substances of the same elementary system are called allotropes or allotropic modifications. In the case of oxygen, there are two allotropic modifications: "normal" dioxygen (O2) and trioxygen (O3) or ozone.
allotropy → alotropija
Allotropy (Gr. allos, other, and tropos, manner) is the phenomenon of an element existing in two or more physical forms in the same physical state. The difference between the forms involves either crystaline structure (white, red and black phosphorus), the number of atoms in the molecule of a gas (diatomic oxygen and triatomic ozone), or the molecular structure of a liquid (liquid helium an helium II).
In some cases, the allotropes are stable over a temperature range, with a definite transition point at which one changes into the other. For instance, tin has two allotropes: white (metallic) tin stable above 13.2 °C and grey (nonmetallic) tin stable below 13.2 °C. This form allotropy is called enantiotropy. Form of allotropy, in which there is no transition temperature at which the two are in equilibrium, is called monotropy.
Allotropy does not apply to the substance existing in different physical states as, for example, when ice melts and changes from solid ice to liquid water.
Allotropy is generally restricted to describing polymorphic behaviour in elements, while polymorphism may refer to any material having multiple crystal structures.
arsenic → arsen
Arsenic was discovered by Albertus Magnus (Germany) in 1250. The origin of the name comes from the Greek word arsenikon meaning yellow orpiment. It is steel-grey, brittle semi-metal. Resists water, acids and alkalis. Tarnishes in air, burns in oxygen. Highly toxic by inhalation or ingestion. Arsenic is found in mispickel (arsenopyrite). Many of its compounds are deadly poison and used as weed killer and rat poison. Used in semiconductors. Some compounds, called arsenides, are used in the manufacture of paints, wallpapers and ceramics.
atmosphere → atmosfera
1. Atmosphere is the column of air which is extending several hundred kilometers above the surface the Earth's surface. The density of this air decreases as you proceed up from the surface. The air in the atmosphere consists of 78 % nitrogen, 21 % oxygen, and 0.9 % argon. The remaining 0.1 % of the atmosphere consists of ozone, water vapor, carbon dioxide, methane, helium, and neon. The atmosphere is divided into different regions. The lowest two layers are the troposphere (the layer closest to the earth) and the stratosphere respectively. These two layers contain more than 99 % of the atmospheric molecules.
2. Standard atmosphere (atm) is an obsolete pressure and stress unit which should be discontinued. It is unit of pressure equal to the air pressure measured at mean sea level.
1 atm = 101 325 Pa
Technical atmosphere (at) is an obsolete MKpS pressure and sttress derived unit.
1 at = 98 066.5 Pa
1 atm = 1.033 227 453 at
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.
chalcogens → halkogeni elementi
Chalcogens are the Group 16 elements: oxygen (O), sulphur (S), selenium Se), tellurium (Te), and polonium (Po). Compounds of these elements are called chalcogenides.
combustion → gorenje
Combustion is a phenomenon when a substance is combined with oxygen in the presence of a flame accompanied by the production of heat and light. Combustion requires a supply of both fuel and oxygen (air) and can take place in the open atmosphere such as an open fire, or in a closed system, such as a car engine.
Citing this page:
Generalic, Eni. "Oxygen meter for oxygen concentrator." Croatian-English Chemistry Dictionary & Glossary. 29 June 2022. KTF-Split. {Date of access}. <https://glossary.periodni.com>.
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