CHEMISTRY GLOSSARY

activated complex    →   aktivirani kompleks

Activated complex is an intermediate structure formed in the conversion of reactants to products. The activated complex is the structure at the maximum energy point along the reaction path; the activation energy is the difference between the energies of the activated complex and the reactants.

agarose    →   agaroza

Agarose is a polysaccharide obtained from agar that is used for a variety of life science applications especially in gel electrophoresis. The structure of agarose consists of alternating (1→3)-linked β-D-galactopyranose and (1→4)-linked 3,6-anhydro-α-L-galactopyranose.

alanine    →   alanin

Alanine is hydrophobic amino acids with aliphatic side chain. It is the second simplest amino acid, but used the most in proteins. The nonpolar hydrophobic amino acids tend to cluster together within proteins, stabilizing protein structure by means of hydrophobic interactions. Alanine is a nonessential amino acid, meaning it can be manufactured by the human body, and does not need to be obtained directly through the diet.

• Abbreviations: Ala, A
• IUPAC name: 2-aminopropanoic acid
• Molecular formula: C₃H₇NO₂
• Molecular weight: 89.09 g/mol

amines    →   amini

Amines are compounds formally derived from ammonia by replacing one, two, or three hydrogen atoms by hydrocarbyl groups, and having the general structures RNH₂ (primary amines), R₂NH (secondary amines), R₃N (tertiary amines). Examples are methylamine, CH₃NH₂; dimethylamine, CH₃NHCH₃; and trimethylamine, (CH₃)₃N.

anion exchange    →   anionski izmjenjivač

An anionic resin has negative ions built into its structure and therefore exchanges positive ions. In an anion exchange, the side groups are ionised basic groups, such as (-NH₂, -NRH, -NR₂, -NR₃⁺) to which anions OH^- are attached. The exchange reaction is one in which different anions in the solution displace the OH^- from the solid.

bcc    →   bcc

bcc is abbreviation for body-centered cubic lattice.

allotropy    →   alotropija

Allotropy (Gr. allos, other, and tropos, manner) is the phenomenon of an element existing in two or more physical forms in the same physical state. The difference between the forms involves either crystaline structure (white, red and black phosphorus), the number of atoms in the molecule of a gas (diatomic oxygen and triatomic ozone), or the molecular structure of a liquid (liquid helium an helium II).

In some cases, the allotropes are stable over a temperature range, with a definite transition point at which one changes into the other. For instance, tin has two allotropes: white (metallic) tin stable above 13.2 °C and grey (nonmetallic) tin stable below 13.2 °C. This form allotropy is called enantiotropy. Form of allotropy, in which there is no transition temperature at which the two are in equilibrium, is called monotropy.

Allotropy does not apply to the substance existing in different physical states as, for example, when ice melts and changes from solid ice to liquid water.

Allotropy is generally restricted to describing polymorphic behaviour in elements, while polymorphism may refer to any material having multiple crystal structures.

biochemistry    →   biokemija

Biochemistry is the study of the chemistry of living organisms, especially the structure and function of their chemical components (principally proteins, carbohydrates, lipids and nucleic acids).

Bravais lattice    →   Bravaisova rešetka

Bravais lattice is a set of points constructed by translating a single point in discrete steps by a set of basis vectors. The French crystallographer Auguste Bravais (1811-1863) established that in three-dimensional space only fourteen different lattices may be constructed. All crystalline materials recognised till now fit in one of these arrangements. The fourteen three-dimensional lattices, classified by crystal system, are shown to the bottom.

Crystal system	Bravais lattices
cubic a=b=c α=β=γ=90°
	simple cubic	body-centered cubic	face-centered cubic
tetragonal a=b≠c α=β=γ=90°
	simple tetragonal	body-centered tetragonal
orthorhombic a≠b≠c α=β=γ=90°
	simple orthorhombic	base-centered orthorhombic	body-centered orthorhombic	face-centered orthorhombic
monoclinic a≠b≠c α=γ=90°≠β
	simple monoclinic	base-centered monoclinic
hexagonal a=b≠c α=β=90° γ=120°
	hexagonal
rhombohedral a=b=c α=β=γ≠90°
	rhombohedral
triclinic a≠b≠c α≠β≠γ≠90°
	triclinic

buffer    →   pufer otopina

Buffer is a solution designed to maintain a constant pH when small amounts of a strong acid or base are added. Buffers usually consist of a fairly weak acid and its salt with a strong base. Suitable concentrations are chosen so that the pH of the solution remains close to the pK_a of the weak acid.