CHEMISTRY GLOSSARY

triclinic lattice    →   triklinska rešetka

Triclinic 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°.

Bragg angle    →   Braggov kut

Bragg angle (Θ) is the angle between an incident X-ray beam and a set of crystal planes for which the secondary radiation displays maximum intensity as a result of constructive interference. British physicist Sir William Henry Bragg and his son Sir William Lawrence Bragg developed a simple relation for scattering angles, now call Bragg’s law.

which relates the angle θ between a crystal plane and the diffracted X-ray beam, the wavelength λ of the x-rays, the crystal plane spacing d, and the diffraction order n (any integer).

The diffraction experiment as presently considered is intended to provide quantitative information on the lattice constant and shape characteristics of the unit cell.

crystal system    →   kristalni sustav

Crystal system is a method of classifying crystalline substances on the basis of their unit cell. There are seven unique crystal systems. The simplest and most symmetric, the cubic (or isometric) system, has the symmetry of a cube. The other six systems, in order of decreasing symmetry, are hexagonal, tetragonal, rhombohedral (also known as trigonal), orthorhombic, monoclinic and triclinic.

Crystal system	Unit-cell	Conditions on unit-cell edges and angles
cubic		a=b=c α=β=γ=90°
hexagonal		a≠c α=γ=90° β=120°
tetragonal		a=b≠c α=β=γ=90°
rhombohedral		a=b=c α=β=γ≠90°
orthorhombic		a≠b≠c α=β=γ=90°
monoclinic		a≠b≠c α=γ=90°≠β
triclinic		a≠b≠c α≠β≠γ≠90°

alabaster    →   alabaster

Alabaster is a monoclinic mineral form of hydrated calcium sulphate. It is a pure fine-grained translucent form of gypsum. CaSO₄·2H₂O.

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

amide    →   amid

Amide is an organic compound that contains a carbonyl group bound to nitrogen. The simplest amides are formamide (HCONH₂) and acetamide (CH₃CONH₂).

Avogadro, Amadeo    →   Avogadro, Amadeo

Amadeo Avogadro (1776-1856) is an Italian chemist and physicist that proposed a correct molecular explanation for Gay-Lussac’s law of combining volumes. His work provided a simple way to determine atomic weights and molecular weights of gases. He is published a theory about the movement of particles in gases that became known as Avogadro’s Law.

bcc    →   bcc

bcc is abbreviation for body-centered cubic lattice.

crystal    →   kristal

Crystal is a solid with a regular geometric shape, having a characteristic internal structure and enclosed by symmetrically arranged plane surfaces, intersecting at definite and characteristic angles. In crystals the particles (atoms, ions, or molecules) have a regular three-dimensional repeating arrangement in space. This is called the crystal structure. The crystal lattice is the arrangement of points in space at which the particles are positioned.

element    →   element

Element is a substance that cannot be decomposed into simpler substances. In an element, all the atoms have the same number of protons or electrons, although the number of neutrons my vary.