Crystal Symmetry Definitions

Crystals possess unique structural arrangements that define their symmetry. Key terms relate to how different parts of the crystal relate to each other through symmetry operations like inversion or reflection.

Centrosymmetric Crystal Properties

A centrosymmetric crystal has a center of symmetry. If you draw a line from any point on the crystal's surface through the exact center and extend it the same distance, you will find an identical point on the opposite side. This means features like faces appear mirrored across the center. For instance, a face on one side would be opposite an identical face on the other.

Non-centrosymmetric Crystal Properties

Conversely, a non-centrosymmetric crystal lacks a center of symmetry. In such crystals, the symmetry operations do not lead to identical points or features being diametrically opposite. The question describes a specific case: "a face on one side is opposite to a point on the other". This condition indicates the absence of a center of symmetry, where a face doesn't have an identical face opposite it.

Analyzing Crystal Definitions

Let's examine the options in light of the description:

• Enantiomorphous: These are crystals that are non-superimposable mirror images of each other (chiral). This doesn't directly match the face-to-point description.
• Centrosymmetric: Ruled out because a face opposite a point violates the definition of having an identical face opposite.
• Non-centrosymmetric: This perfectly matches the description of having a face opposite a point, indicating a lack of central symmetry.
• Hemihedral: This describes crystals showing fewer faces than expected for their symmetry class, not specifically a face-opposite-point relationship.

Therefore, the description directly corresponds to the definition of a non-centrosymmetric crystal.