CHEMISTRY GLOSSARY

borane    →   borani

Borane is any of the group of compounds of boron and hydrogen (B₂H₆, B₄H₁₀, B₅H₉, B₅H₁₁...), many of which can be prepared by action of acid on magnesium boride (Mg₃B₂). Boranes are a remarkable group of compounds in that their structures cannot be described using the conventional two-electron covalent bond model.

branched chain    →   razgranati lanac

Branched chain is an open chain of atoms with one or more side chains attached to it.

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.

isomer    →   izomer

Isomers are compounds that have identical molecular formulae but differ in the nature or sequence of bonding of their atoms (structural isomerism) or in the arrangement of their atoms in space (stereoisomerism).

Lewis acid    →   Lewisova kiselina

Lewis acid is an agent capable of accepting a pair of electrons to form a coordinate bond.

Lewis base    →   Lewisova baza

Lewis base is an agent capable of donating a pair of electrons to form a coordinate bond.

Lewis, Gilbert N.    →   Lewis, Gilbert N.

Gilbert Newton Lewis (1875-1946) is an American chemist whose theory of the electron pair fostered understanding of the covalent bond and extended the concept of acids and bases.

carbon    →   ugljik

Carbon has been known since ancient times. The origin of the name comes from the Latin word carbo meaning charcoal. Graphite form of carbon is a black, odourless, slippery solid. Graphite sublimes at 3825 °C. Diamond form is a clear or colored; an extremely hard solid. C60 is Buckminsterfullerine. Carbon black burns readily with oxidants. Carbon is made by burning organic compounds with insufficient oxygen. There are close to ten million known carbon compounds, many thousands of which are vital to organic and life processes. Radiocarbon dating uses the carbon-14 isotope to date old objects.

cellulose    →   celuloza

Cellulose, (C₆H₁₀O₅)_n, is a polysaccharide that consists of a long unbranched chain of glucose units linked by (1→4)-β-glycoside bonds. Nature uses cellulose primarily as a structural material to impart strength and rigidity to plants. Leaves, grasses, and cotton are primarily cellulose. The fibrous nature of extracted cellulose has led to its use in textile industry for the production of cotton, artificial silk, etc. Cellulose also serves as raw material for the manufacture of cellulose acetate, known commercially as acetate rayon, and cellulose nitrate, known as guncotton. Gunncotton is the major ingredient in smokeless powder, the explosive propellant used in artillery shells and in ammunition for firearms.

cement    →   cement

Cement is any various substances used for bonding or setting to a hard material. Portland cement is a mixture of calcium silicates and aluminates made by heating limestone (CaCO₃) with clay (containing aluminosilicates) in a kiln. The product is ground to a fine powder. When mixed with water it settles in a few hours and then hardens over a longer period of time due to the formation of hydrated aluminates and silicates.