Question

Total number of planes, axes and centre of symmetries in a crystal is termed as a) elements of symmetry (b) symmetries c) symmetry operations

Short answer

The correct answer is (a) elements of symmetry

Step-by-step solution

Understanding the Terms

Understand the mentioned terms: planes of symmetry, axis of symmetry and centre of symmetry. In crystallography, these are essential elements contributing to the symmetrical characteristic of a crystal.

Recognize the Correct Answer

Recognize the correct definitions. The total number of planes, axes, and center of symmetries in a crystal essentially constitute the elements of symmetry in the crystal structure.

Key concepts

Planes of Symmetry

Think of a plane of symmetry like a magical mirror that splits a shape into two equal parts, each a mirror image of the other. Imagine slicing a clean apple into two equal halves. Each half looks identical but reversed, as if you are seeing one side in a mirror. In the world of crystals, planes of symmetry work in the same magical way. They let us divide a crystal into two symmetrical parts, reinforcing the idea of balance and uniformity in its structure.

Here are some key points to help you understand planes of symmetry in crystals:

• Planes of symmetry are imaginary flat surfaces.
• They divide an object into two equal halves that are mirror images.
• Crystals can have multiple planes of symmetry, displaying their beautiful and intricate designs.

Understanding these planes help us understand why crystals have their unique charm and delicate designs.

Axes of Symmetry

Axes of symmetry are the invisible lines around which an object can rotate and still look the same from various angles. Picture twirling a pencil around on a table. No matter how many times you rotate it around its central axis, the pencil always looks the same.

In crystallography, these axes bring out one of the most intriguing features of a crystal's symmetrical pattern.

• An axis of symmetry allows an object to be rotated around it and look unchanged at specific angles.
• Crystals can have one or more axes of symmetry, showcasing different kinds of rotational semblance.
• These axes help classify the crystal into different symmetry groups.

Axes of symmetry emphasize the rotational harmony within the crystal, making them fascinating objects of study.

Centre of Symmetry

Imagine having an invisible point within an object, such that if you moved away from it along any direction, you would meet a similar feature as if reflected back through that point. This reflects the idea of the center of symmetry.

A center of symmetry implies that for every part of the crystal, there is an identical part on the opposite side, equally distanced from this central point. Here's how it operates in crystals:

• The centre of symmetry is a point from which every structure in one direction has an identical counterpart exactly opposite.
• It exists within objects where for every element, there is a twin part directly across the center point.
• Having a centre of symmetry indicates that the object appears identical from opposite sides.

This concept fortifies the balanced and symmetrical nature of crystals, contributing to their overall beauty and allure.