CHEMISTRY GLOSSARY

invertase    →   invertaza

Invertase (sucrase, saccharase, beta-fructofuranosidase) is an enzyme present in yeast and in the intestinal juice of animals that catalyze the hydrolysis of table sugar (sucrose, saccharose) to the simple sugars, glucose and fructose. This equimolar mixture of glucose and fructose is called invert sugar.

brass    →   mjed

Brasses are alloys of copper and zinc (generally 5 % to 40 %). Brass has been known to man since prehistoric times, long before zinc itself was discovered. It was produced by melting copper together with calamine, a zinc ore. Its ductility reaches a maximum with about 30 % zinc and its tensile strength with 45 % although this property varies greatly with the mechanical and heat treatment of the alloy. Typical applications included gears, plumbing ware fittings, adapters, valves and screw machine products. The French horn is a valved brass wind instrument.

Brass may contain small amounts of other alloying elements, such as aluminum, lead, tin, or nickel. Lead can be added as an alloying element resulting in a brass that can be rapidly machined and produces minimal tool wear. Additions of aluminium, iron and manganese to brass improve strength, whilst silicon additions improve wear resistance. Brass containing tin (< 2 % ) is less liable to corrosion in seawater; it is sometimes called naval brass and is used in naval construction.

lactase    →   laktaza

Lactase is an enzyme that catalyzes the hydrolysis of the disaccharide lactose (milk sugar) to the simple sugars glucose and galactose. Lactose intolerance is the inability to digest lactose. Symptoms can include abdominal pain, abdominal bloating, gas, diarrhea, and nausea.

monomer    →   monomer

Monomer is a simple molecule which is capable of combining with a number of like or unlike molecules to form a polymer. Monomer is repeating structure unit within a polymer.

carbohydrate    →   ugljikohidrat

Carbohydrates (often called carbs for short) are polyhydroxy aldehydes or ketones, or substances that yield such compounds on hydrolysis. They are also known as saccharides, a term derived from the Latin word saccharum for sugar. Carbohydrates are the most abundant class of compounds in the biological world, making up more than 50 % of the dry weight of the Earth’s biomass. Every type of food we eat can have its energy traced back to a plant. Plants use carbon dioxide and water to make glucose, a simple sugar, in photosynthesis. Other carbohydrates such as cellulose and starch are made from the glucose. Light from the sun is absorbed by chlorophyll and this is converted to the energy necessary to biosynthesize carbohydrates

The term carbohydrate was applied originally to monosaccharides, in recognition of the fact that their empirical composition can be expressed as C_x(H₂O)_y. Later structural studies revealed that these compounds were not hydrates but the term carbohydrate persists.

Carbohydrates are generally classed as either simple or complex. Simple sugars, or monosaccharides, are carbohydrates that can’t be converted into smaller subunits by hydrolysis. Complex carbohydrates are made of two (disaccharides) or more (oligosaccharides, polysaccharides) simple sugars linked together by acetal (glycosidic) bonds and can be split into the former by hydrolysis.

copolymer    →   kopolimer

Copolymers are also known as heteropolymers. They are made from two (or more) different monomers, which usually undergo a condensation reaction with the elimination of a simple molecule, such as ammonia or water. A typical example is the condensation of 1,6-diaminohexane (hexamethylenediamine) with hexanedioic acid (adipic acid) to form nylon 6,6.

The properties of a polymeric plastic can most easily be modified if it is a copolymer of two or more different monomers, e.g. acrylonitrile-butadiene-styrene copolymer (ABS). Varying the proportions of the component monomers can preselect its properties.

quasicrystal    →   kvazikristal

Quasicrystal is a solid having conventional crystalline properties but whose lattice does not display translational periodicity.

solid solution    →   čvrste otopine

Solid solution is a crystalline material that is a mixture of two or more components, with ions, atoms, or molecules of one component replacing some of the ions, atoms of the other component in its normal crystal lattice.

synthesis    →   sinteza

Synthesis is a formation of a complex product from simpler reactants. For example, water can be synthesised from oxygen and hydrogen gas:

vacancy    →   vakancija

Vacancy is a missing atom or ion in a crystal lattice.