Fractional crystallisation is a method of separating a mixture of soluble solids by dissolving them in a suitable hot solvent and then lowering the temperature slowly. The least soluble component will crystallise out first, leaving the other components in the solution. By controlling the temperature, it is sometimes possible to remove each component in turn.
Heat of crystallization or enthalpy of crystallization is the heat evolved or absorbed when one mole of given substance crystallises from a saturated solution of the same substance.
Cubic crystal system is also known as the isometric system. The Isometric crystal system characterizes itself by its three equivalent crystallographic axes perpendicular to each other.
a = b = c
α = β = γ = 90°
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 |
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a=b=c α=β=γ=90° |
hexagonal |
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a≠c α=γ=90° β=120° |
tetragonal |
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a=b≠c α=β=γ=90° |
rhombohedral |
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a=b=c α=β=γ≠90° |
orthorhombic |
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a≠b≠c α=β=γ=90° |
monoclinic |
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a≠b≠c α=γ=90°≠β |
triclinic |
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a≠b≠c α≠β≠γ≠90° |
Crystal lattice is a three-dimensional array of points that embodies the pattern of repetition in a crystalline solid. Don’t mix up atoms with lattice points: lattice points are infinitesimal points in space - atoms are physical objects.
Lattice constants are parameters specifying the dimensions of a unit cell in a crystal lattice, specifically the lengths of the cell edges and the angles between them.
Lattice energy is the energy per ion pair required to separate completely the ions in a crystal lattice at a temperature of absolute zero.
Supercooled liquids are liquids at temperatures below their normal freezing points.
Hexagonal crystal system is based on four crystallographic axes. The system of crystallographic axes of the hexagonal crystal system consists of three equivalent horizontal (equatorial) axes of which the positive ends make an angle of 120°. These axes are sometimes denoted as a, b and d axes. The fourth axis is (c) is perpendicular to and shorter or longer than the other three.
X-ray crystallography is a determination of a three dimensional arrangements of atoms in a crystal by analysis of X-ray diffraction patterns.
Generalic, Eni. "Tekući kristal." Croatian-English Chemistry Dictionary & Glossary. 29 June 2022. KTF-Split. {Date of access}. <https://glossary.periodni.com>.
Glossary
Periodic Table