Crystallography and Crystal Systems

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Questions and Answers

What are the Miller indices for the basal pinacoid?

(001)

How many faces does the orthorhombic bipyramid have?

What symmetry elements are present in the tetragonal system?

5 axes, 5 planes, and a center.

What are the Miller indices for the orthorhombic prism?

(hk0) Signup and view all the answers

What are the conditions for the crystal to be classified as a center ' positive' type?

The center must have unequal edges (a ≠ b ≠ c) and unequal angles (α ≠ β ≠ δ ≠ 90). Signup and view all the answers

List three crystal forms included in the provided crystal forms.

Basal pinacoid, side pinacoid, and front pinacoid. Signup and view all the answers

What Miller index corresponds to the hemi prism crystal form?

(hk0) Signup and view all the answers

Identify the Miller indices for the basal pinacoid crystal form.

(001) Signup and view all the answers

How are the hemi a-dome and hemi b-dome different in terms of their Miller indices?

Hemi a-dome is (0kL) and hemi b-dome is (h0L). Signup and view all the answers

What is the crystalographic element condition for the tetragonal system?

In the tetragonal system, crystalographic elements are defined as (a = b ≠ c) and (α = β = δ = 90). Signup and view all the answers

Identify the forms associated with the monoclinic system.

The forms associated with the monoclinic system include basal pinacoid (001), side pinacoid (010), and front pinacoid (100). Signup and view all the answers

What symmetry elements are present in the triclinic system?

The triclinic system has no axes of symmetry or planes of symmetry. Signup and view all the answers

What are the first and second order tetragonal prisms denoted as?

The first order tetragonal prism is denoted as (hh0) and the second order as (h00). Signup and view all the answers

How many forms does a ditetragonal bipyramid have, and what is its notation?

A ditetragonal bipyramid has 16 forms and is denoted as (hkL). Signup and view all the answers

What is the number of axes present in the orthorhombic system?

There are 3 axes in the orthorhombic system. Signup and view all the answers

What are the values of the angles in the orthorhombic crystal system?

The angles are all equal to 90 degrees: $\alpha = \beta = \delta = 90$. Signup and view all the answers

How many planes of symmetry are found in the orthorhombic system?

There are 3 mirror planes in the orthorhombic system. Signup and view all the answers

In the orthorhombic system, what is the relationship between the lengths of the axes?

The lengths of the axes are unequal: $a \neq b \neq c$. Signup and view all the answers

What is the significance of the center in the orthorhombic symmetry?

The center is positively defined, indicating a symmetric point in the crystal. Signup and view all the answers

Study Notes

Crystallography

Crystallography is a study of crystals.
It focuses on the arrangements, structures, and properties of crystals.
It examines the systematic arrangements of atoms in a crystalline material, describing their geometrical patterns.

Orthorhombic System

Elements of Symmetry:
- Axes: 3 (a, b, c) 3°
- Planes: 3m
- Center: +ve
Crystallographic elements:
- (a ≠ b ≠ c), (α = β = δ = 90°)
- The axes are not equal in length.
- The angles between the axes are 90°.

Crystal Forms (Orthorhombic)

1- Basal pinacoid: (001) 2F
2- Side pinacoid: (010) 2F
3- Front pinacoid: (100) 2F
4- Orthorhombic prism: (hk0) 4F
5- a-dome: (0kL) 4F
6- b-dome: (h0L) 4F
7- Orthorhombic bipyramid: (hkL) 8F

Tetragonal System

Elements of symmetry:
- Axes: 5 (1c, 20a, 2b,20 between axes)
- Planes: 5m
- Center: +ve
Crystallographic elements:
- (a = b ≠ c), (α = β = δ = 90°)
- Two axes are equal in length but are longer than the third one.
- Angles between the axes are 90°.

Crystal Forms (Tetragonal)

1- Basal pinacoid: (00L) 2F
2- Tetragonal prism (first order): (h00) 4F
3- Tetragonal prism (second order): (0h0) 4F
4- Ditetragonal prism: (hk0) 8F
5- Tetragonal bipyramid (first order): (hhl) 8F
6- Tetragonal bipyramid (second order): (h0l) 8F
7- Ditetragonal bipyramid: (hkL) 16F

Monoclinic System

Elements of symmetry:
- Axes: 1b
- Planes: 1m
- Center: +ve
Crystallographic elements:
- (a ≠ b ≠ c), (α = δ = 90° ≠ β > 90°)
- Only one axis is at a right angle to the other two axes.

Crystal Forms (Monoclinic)

1- Basal pinacoid: (001) 2F
2- Side pinacoid: (010) 2F
3- Front pinacoid: (100) 2F
4- hemi b-dome:(h0L) 2F
5- Monoclinic prism: (hk0) 4F
6- a-dome: (0kL) 4F
7- hemi-bipyramid: (hkL) 4F

Triclinic System

Elements of symmetry:
- Axes: no axes
- Planes: no planes
- Center: +ve
Crystallographic elements:
- (a ≠ b ≠ c), (α ≠ β ≠ δ ≠ 90°)
- No axes or planes of symmetry.

Crystal Forms (Triclinic)

1- Basal pinacoid: 001 2F
2- Side pinacoid: 010 2F
3- Front pinacoid: 100 2F
4- hemi prism: hk0 2F
5- hemi a-dome: 0kL 2F
6- hemi b-dome: h0L 2F
7- quarter bipyramid: hkL 2F

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Description

Explore the fundamentals of crystallography, focusing on the orthorhombic and tetragonal crystal systems. This quiz examines the symmetry elements, crystallographic elements, and different crystal forms. Test your knowledge on the arrangements, structures, and properties of crystals.