CHEMISTRY GLOSSARY

orthorhombic crystal system    →   ortorompski kristalni sustav

Orthorhombic crystal system is also known as the rhombic system. Minerals of the orthorhombic crystal system are referred to three mutually perpendicular axes, each of which is of a different length than the others.

rhombohedral crystal system    →   romboedarski kristalni sustav

Rhombohedral crystal system is also known as the trigonal system. The crystallographic axes used in this system are of equal length. None of the axes are perpendicular to any other axis.

rhombohedral lattice    →   romboedarska rešetka

Rhombohedral (or trigonal) lattice has one lattice point at the each corner of the unit cell. It has unit cell vectors a=b=c and interaxial angles α=β=γ≠90°.

simple cubic lattice    →   jednostavna kubična rešetka

Simple or primitive cubic lattice (sc or cubic-P) has one lattice point at the each corner of the unit cell. It has unit cell vectors a = b = c and interaxial angels α=β=γ=90°.

The simplest crystal structures are those in which there is only a single atom at each lattice point. In the sc structures the spheres fill 52 % of the volume. The number of atoms in a unit cell is one (8×1/8 = 1). This is only one metal (α-polonium) that have the sc lattice.

simple monoclinic lattice    →   jednostavna monoklinska rešetka

Simple or primitive monoclinic lattice (monoclinic-P) has one lattice point at the each corner of the unit cell. It has unit cell vectors a≠b≠c and interaxial angles α=γ=90°≠β.

simple orthorhombic lattice    →   jednostavna ortorompska rešetka

Simple or primitive orthorhombic lattice (orthorhombic-P) has one lattice point at the each corner of the unit cell. It has unit cell vectors a≠b≠c and interaxial angles α=β=γ=90°.

simple tetragonal lattice    →   jednostavna tetragonska rešetka

Simple or primitive tetragonal lattice (tetragonal-P) has one lattice point at the each corner of the unit cell. It has unit cell vectors a=b≠c and interaxial angles α=β=γ=90°.

starch    →   škrob

Starch (C₆H₁₀O5)_x is a polysaccharide used by plants to stockpile glucose molecules. It is the major component of flour, potatoes, rice, beans, corn, and peas. Starch is a mixture of two different polysaccharides: amylose (about 20 %), which is insoluble in cold water, and amylopectin (about 80 %), which is soluble in cold water. Amylose is composed of unbranched chains of D-glucose units joined by α(1→4)-glycosidic linkages. Unlike amylose, which are linear polymers, amylopectin contains α(1→6)-glycoside branches approximately every 25 glucose units.

Starch digestion begins in the mouth via the action of amylase, a digestive enzyme present in saliva. The process is completed in the small intestine by the pancreatic amylase. The final products of starch digestion, glucose molecules, are absorbed into the intestinal bloodstream and transported to the liver. Like most enzymes, glycosidases are highly selective in their action. They hydrolyze only the α-glycoside links in starch and leave the β-glycoside links in cellulose untouched. Starch is important food stuff and is used in adhesives, and sizes, in laundering, pharmacy and medicine.

sucrose    →   saharoza

Sucrose (saccharose), or ordinary table sugar, is a disaccharide in which α-D-glucopyranose and β-D-fructofuranose are joined at their anomeric carbons by a glycosidic bond. There are no hemiacetals remaining in the sucrose and therefore sucrose is not a reducing sugar and does not exhibit mutarotation. Sugar is a white crystalline sweet compound found in many plants and extracted from sugar cane and sugar beet. It is used as a sweetening agent in food and drinks. If heated to 200 °C, sucrose becomes caramel. When sucrose is hydrolyzed it forms an equimolar mixture of glucose and fructose. This mixture of monosaccharides is called invert sugar. Honeybees have enzymes called invertases that catalyze the hydrolysis of sucrose. Honey, in fact, is primarily a mixture of glucose, fructose, and sucrose.

tetragonal crystal system    →   tetragonski kristalni sustav

Minerals of the tetragonal crystal system are referred to three mutually perpendicular axes. The two horizontal axes are of equal length, while the vertical axis is of different length and may be either shorter or longer than the other two.