CHEMISTRY GLOSSARY

petrochemicals    →   petrokemikalije

Petrochemicals are the industrially important organic chemicals which are derived from petroleum or natural gas.

pigment    →   pigment

Pigments are the substances that give paint colour. Pigments are derived from natural or synthetic materials that have been ground into fine powders. A pigment is different from a dye in that a pigment is insoluble in the media in which it is used.

Pigment is an organic substance found in plant and animal cells that creates colouring.

pit coal    →   kameni ugljen

Pit coal is natural black coal that has a carbon content of 75 %-90 %. It is an important raw material in organic industry

Gratzel solar cell    →   Gratzelova sunčeva ćelija

Grätzel solar cell is photoelectrochemical cell, developed by Michael Grätzel and collaborators, simulates some characteristics of the natural solar cell, which enables photosynthesis take place. In natural solar cell the chlorophyll molecules absorb light (most strongly in the red and blue parts of the spectrum, leaving the green light to be reflected). The absorbed energy is sufficient to knock an electron from the excited chlorophyll. In the further transport of electron, other molecules are involved, which take the electron away from chlorophyll. In Grätzel cell, the tasks of charge-carrier generation and transport are also assigned to different species.

His device consists of an array of nanometre-sized crystallites of the semiconductor titanium dioxide, welded together and coated with light-sensitive molecules that can transfer electrons to the semiconductor particles when they absorb photons. So, light-sensitive molecules play a role equivalent to chlorophyll in photosynthesis. In Grätzel cell, the light-sensitive molecule is a ruthenium ion bound to organic bipyridine molecules, which absorb light strongly in the visible range; titanium dioxide nanocrystals carry the received photoexcited electrons away from electron donors. On the other hand, a donor molecule must get back an electron, so that it can absorb another photon. So, this assembly is immersed in a liquid electrolyte containing molecular species (dissolved iodine molecules) that can pick up an electron from an electrode immersed in the solution and ferry it to the donor molecule. These cells can convert sunlight with efficiency of 10 % in direct sunlight and they are even more efficient in diffuse daylight.

latex    →   lateks

Latex, also known as rubber or natural latex, is a milky fluid derived from the rubber tree. The latex is a colloid of caoutchouc (25-35%) dispersed in water (60-75%), which forms rubber by coagulation. The term is also applied to artificial emulsions of natural or artificial rubber, or of certain synthetic resins (such as polyvinyl acetate or polyvinyl chloride). It is used in a wide variety of consumer products, including rubber gloves, tubing, condoms, rubber bands, etc.

macromolecule    →   makromolekule

Macromolecule is a molecule of high relative molecular mass (molecular weight), the structure of which essentially comprises the multiple repetitions of units derived, actually or conceptually, from molecules of low relative molecular mass. The types of macromolecules are natural and synthetic polymers, carbohydrates, lipids, proteins etc. Cellulose is a polysaccharide that is made up of hundreds, even thousands of glucose molecules strung together.

Planck constant    →   Planckova konstanta

Planck constant (h) is a constant that, when multipled by the frequency of radiation gives the quantity of energy contained in one quantum.

Equal to 6.626 075 5(40)·10^-34 J s. It was named after Max Planck (1858-1947).

protein    →   bjelančevina

Proteins are natural organic compounds of animal or herbal origin, essential in diet. They are natural polymers developed from a crowd of interconnecting monomers of amino acids, with relative molecular masses amounting up to a few million.

organic    →   organski

1. Organic refers to any chemical compound based on carbon (C) with the exception of some of the simple compounds of carbon, such as carbon dioxide, which are frequently classified as inorganic compounds. Additional elements that are commonly found in organic compounds are hydrogen (H), nitrogen (N), oxygen (O), phosphorus (P) and sulfur (S).

2. Organic or organically-grown foods are grown or raised without synthetic fertilizers, pesticides, growth stimulators, or antibiotics and other drugs. Pests are controlled by cultivation techniques and the use of pesticides derived from natural sources and the use of natural fertilizers. In addition, organically grown foods must also be stored without the use of chemicals such as artificial additives and preservatives, and without food irradiation.

osmium    →   osmij

Osmium was discovered by Smithson Tennant (England) in 1803. The origin of the name comes from the Greek word osme meaning smell. It is hard fine black powder or hard, lustrous, blue-white metal. Unaffected by air, water and acids. Characteristic acrid, chlorine like odour due to tetroxide compound. Osmium tetroxide highly toxic. Osmium is obtained from the same ores as platinum. Used to tip gold pen points, instrument pivots, to make electric light filaments. Used for high temperature alloys and pressure bearings. Very hard and resists corrosion better than any other.