CHEMISTRY GLOSSARY

micron    →   mikron

Micron (μ) is an obsolete name for micrometer (μm).

microanalysis    →   mikroanaliza

Microanalysis is a sum of analytical procedures used for researching of very small quantities of matter (around 1 mg).

microchemistry    →   mikrokemija

Microchemistry is a branch of chemistry that concerns isolating, identifying and an analysis of very small quantities of sample (few mg). It uses delicate reactions, special equipment and microscopes.

electron microscope    →   elektronski mikroskop

Electron microscope is a form of microscope that uses a beam of electrons instead of a beam of light (as in the optical microscope) to form a large image of a very small object. In optical microscopes the resolution is limited by the wavelength of the light. High-energy electrons, however, can be associated with a considerably shorter wavelength than light; for example, electrons accelerated to energy of 10⁵ electronvolts have a wavelength of 0.004 nm enabling a resolution of from 0.2 nm to 0.5 nm to be achieved.

microwave radiation    →   mikrovalna radijacija

Microwave radiation is a electromagnetic radiation with wavelength between 3 mm and 30 cm.

microscope    →   mikroskop

Microscope is an instrument that produces enlarged images of small objects. The optical microscopes (light microscope) use visible light and a system of lenses to magnify images. Typical magnification of a light microscope is up to 1500× ("1500 times")with a theoretical resolution limit of around 200 nm. Instead of using light, electron microscopes transmit a beam of electrons through, or onto the surface of, a specimen. An electron beam has a much shorter wavelength than does light, and can reveal structures as small as 2 nm.

agar    →   agar

Agar, also called agar-agar, is an extract of certain species of red algae (of the Gelidium and Gracilaria genera) that is used as a gelling agent in microbiological culture media, foodstuffs, medicine, and cosmetic. The predominant component of agar is agarose, a polysaccharide made up of subunits of the sugar galactose.

colloid    →   koloid

Colloids are systems in which there are two or more phases, with one (the dispersed phase) distributed in the other (the continuous phase). Moreover, at least one of the phases has small dimensions, in the range between 1 nm and 1 μm (10^-9 m – 10^-6 m). Dimension, rather than the nature of the material, is characteristic. In this size range, the surface area of the particle is large with respect to its volume so that unusual phenomena occur, e.g., the particles do not settle out of the suspension by gravity and are small enough to pass through filter membranes. Macromolecules (proteins and other high polymers) are at the lower limit of this range; the upper limit is usually taken to be the point at which the particles can be resolved in an optical microscope.

Colloidal particles may be gaseous, liquid, or solid, and occur in various types of suspensions:

Sols - dispersions of small solid particles in a liquid.

Emulsions - colloidal systems in which the dispersed and continuous phases are both liquids.

Gels - colloids in which both dispersed and continuous phases have a three-dimensional network throughout the material.

Aerosols - colloidal dispersions of liquid or solid particles in a gas.

Foams - dispersions of gases in liquids or solids.

colloid mill    →   koloidni mlin

Colloid mills are machines used to grind aggregates into very fine particles or to apply very high shearing within a fluid to produce colloid suspensions or emulsions in which the particle sizes are less than 1 micrometer. One type of colloid mill is called a disc mill, in which a mixture of a solid and liquid (or two liquids) is passed between two discs a small distance apart, which rotate very rapidly relative to each other. Applications of colloid mills occur in food processing, in paint manufacture, and in the pharmaceutical industry.

diatomaceous earth    →   dijatomejska zemlja

Diatomaceous earth is a naturally occurring siliceous sedimentary mineral compound from microscopic skeletal remains (frustules) of diatoms, unicellular aquatic plants of microscopic size. Their fossilized remains are called diatomite and contains approximately 3000 diatom frustules per cubic millimetre.

Diatomite is relatively inert and has a high absorptive capacity, large surface area, and low bulk density. It consists of approximately 90 % silica, and the remainder consists of compounds such as aluminum and iron oxides. The fine pores in the diatom frustules make diatomite an excellent filtering material for waters, beverages, oils, chemicals, as well as many other products.