CHEMISTRY GLOSSARY
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.
a = b = c
α= β = γ ≠ 90°
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.
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Crystal system
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Unit-cell
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Conditions on unit-cell edges and angles |
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cubic |
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a=b=c α=β=γ=90° |
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hexagonal |
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a≠c α=γ=90° β=120° |
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tetragonal |
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a=b≠c α=β=γ=90° |
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rhombohedral |
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a=b=c α=β=γ≠90° |
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orthorhombic |
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a≠b≠c α=β=γ=90° |
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monoclinic |
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a≠b≠c α=γ=90°≠β |
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triclinic |
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a≠b≠c α≠β≠γ≠90° |
cubic crystal system → kubični kristalni sustav
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°
hexagonal crystal system → heksagonski kristalni sustav
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.
monoclinic crystal system → monoklinski kristalni sustav
Minerals of the monoclinic crystal system are referred to three unequal axes. Two of these axes (a and c) are inclined toward each other at an oblique angle; these are usually depicted vertically. The third axis (b) is perpendicular to the other two and is called the ortho axis. The two vertical axes therefore do not intersect one another at right angles, although both are perpendicular to the horizontal axis.
a ≠ b ≠ c
α = γ = 90° ≠ β
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.
a ≠ b ≠ c
α = β = γ = 90°
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.
a = b ≠ c
α = β = γ = 90°
triclinic crystal system → triklinski kristalni sustav
Minerals of the triclinic crystal system are referred to three unequal axes, all of which intersect at oblique angles. None of the axes are perpendicular to any other axis.
a ≠ b ≠ c
α ≠ β ≠ γ ≠ 90°
anisotropic crystal → anizotropni kristal
Anisotropic crystal is a crystal that exhibits different properties when tested along axes in different directions.
cgs system of units → cgs sustav jedinica
Cgs system of units is a system of units based upon the centimetre, gram, and second. The International System (SI) has supplanted the cgs system.
Citing this page:
Generalic, Eni. "Rhombohedral+crystal+system." Croatian-English Chemistry Dictionary & Glossary. 29 June 2022. KTF-Split. {Date of access}. <https://glossary.periodni.com>.
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