Crystallography Quiz

Crystal Characteristics at Microscopic Level

• Crystals are characterized at a microscopic level by a highly ordered arrangement of atoms, molecules, or ions.
• The repeating unit in a crystal is called the "unit cell."

Crystal Formation and Arrangement

• Different shapes of crystals are caused by variations in the conditions under which they form, such as temperature and pressure.
• The arrangement of atoms, molecules, or ions is influenced by the conditions of formation, affecting the overall shape of the crystal.

Sodium and Chloride Atoms in Table Salt

• In the crystal image of table salt, Sodium (Na) atoms are typically represented as "small white spheres."
• Chloride (Cl) atoms are represented as "large green spheres" in the same crystal structure.

Crystal Formation and Appearance

• Crystals are formed by the combination of specific atoms or molecules that solidify in an ordered structure.
• The macroscopic appearance of crystals is referred to as "crystalline morphology."

Types of Crystals and Their Habits

• Ionic crystals have flat surfaces and sharp angles, contributing to their defined geometric shapes.
• Quartz is an example of a non-geometrical crystal that exhibits a prismatic habit.

Factors Affecting Crystalline Patterns

• The crystalline pattern and shape are affected by environmental conditions during formation, such as temperature variations and impurity levels.
• Unique characteristics, although rare, can help in mineral identification.

Unique Crystal Habits and Terms

• A mineral with a botryoidal habit is "hematite," which appears as grape-like clusters.
• The term for the visible external shape of a sample is "crystal habit."
• Snowflakes form a unique crystal shape characterized by intricate, symmetrical patterns.