CHEMISTRY GLOSSARY

oxygen    →   kisik

Oxygen was discovered by Joseph Priestley (England) in 1774. The origin of the name comes from the Greek words oxy genes meaning acid and forming (acid former). It is colourless, odourless gas; pale blue liquid. Extremely reactive. Forms oxides with nearly all other elements except noble gases. It is the most abundant element in the earth’s crust and makes up almost 21 % of the atmosphere. Oxygen is obtained primarily from liquid air by fractional distillation. Small amounts are made in the laboratory by electrolysis of water. Used in steel making, welding and supporting life. Naturally occurring ozone (O₃) in the upper atmosphere shields the earth from ultraviolet radiation.

ozone    →   ozon

Ozone is an alotropic form of oxygen. It is an unstable blue gas with a pungent odour. It is a powerful oxidising agent. The gas is made by passing oxygen through a silent electric discharge.

phenylalanine    →   fenilalanin

Phenylalanine is hydrophobic amino acids with aromatic side chain. It is quite hydrophobic and even the free amino acid is not very soluble in water. Phenylalanine is large aromatic residue that is normally found buried in the interior of a protein and is important for protein stability. It is an essential amino acid, which means that humans cannot synthesize it, so it must be ingested.

• Abbreviations: Phe, F
• IUPAC name: 2-amino-3-phenylpropanoic acid
• Molecular formula: C₉H₁₁NO₂
• Molecular weight: 165.19 g/mol

poison    →   otrov

Poisons are substance, which upon contact or being introduced into an organism, impair or prevent normal metabolic processes from taking place, thus altering the normal functioning of organs or tissues.

Poisons are molecules or material that tends to collect on a catalyst surface, blocking access to active sites or destroying their activities.

Poisons are substance that can reduce a nuclear reaction by absorbing neutrons, thereby preventing more fission. If enough poisons are present in a reactor core, the chain reaction will die out.

polymer    →   polimer

Polymer is a substance composed of molecules of high relative molecular mass (molecular weight), the structure of which essentially comprises the multiple repetition of units derived, actually or conceptually, from molecules of low relative molecular mass (monomers). In most cases the number of monomers is quite large and is often not precisely known. A single molecule of a polymer is called a macromolecule. Polystyrene is light solid material obtained by polymerisation of styrene (vinyl benzene).

polymerization    →   polimerizacija

Polymerization is a reaction of connecting many monomers in one long molecule whereby polymers are created.

polysaccharide    →   polisaharid

Polysaccharides are compounds consisting of a large number of simple sugars (monosaccharides) linked together by glycosidic bonds. When polysaccharides are composed of a single monosaccharide building block, they are termed homopolysaccharides. Heteropolysaccharides contain two or more different types of monosaccharide. Polysaccharides may have molecular weights of up to several million and are often highly branched. Since they have only the one free anomeric -OH group at the end of a very long chain, polysaccharides aren’t reducing sugars and don’t show noticeable mutarotation. The most common polysaccharides are cellulose, starch, and glycogen.

potential energy    →   potencijalna energija

Potential energy (E_p) is the energy stored in a body or system as a consequence of its position, shape, or state (this includes gravitation energy, electrical energy, nuclear energy, and chemical energy). Gravitational potential energy is the energy associated with the state of separation between bodies that attracts each other via gravitational force. Elastic potential energy is the energy associated with the state of compression or extension of an elastic object. Thermal energy is associated with the random motions of atoms and molecules in a body.

proline    →   prolin

Proline has an aliphatic side chain with a distinctive cyclic structure. It is unusual because it is conformationally restricted. The secondary amino (imino) group of proline residues is held in a rigid conformation that reduces the structural flexibility of polypeptide regions containing proline. It is not an essential amino acid, which means that the human body can synthesize it.

• Abbreviations: Pro, P
• IUPAC name: pyrrolidine-2-carboxylic acid
• Molecular formula: C₅H₉NO₂
• Molecular weight: 115.13 g/mol

redox reaction    →   redoks-reakcija

Redox reaction is an oxidation-reduction reaction is a reaction in which one or more electrons are transferred. When an atom, ion, or molecule loses one or more electrons, it is oxidised. When an atom, ion, or molecule gains one or more electrons, it is reduced.