Comparison Table: Crystalline vs Amorphous Solids with Examples
Understanding the Difference Between Crystalline Solid And Amorphous Solid is essential for students as these solids form the basis of solid-state chemistry. This comparison is frequently tested in school and entrance exams like JEE and NEET due to its conceptual and practical relevance.
Definition of Crystalline Solid
A crystalline solid is a type of solid where constituent particles are arranged in a definite, repeating three-dimensional pattern or lattice. This orderly arrangement leads to distinct physical properties.
Crystalline solids exhibit both long-range and short-range structural order. Their characteristics are covered under the Classification of Solids in solid-state physics.
Definition of Amorphous Solid
An amorphous solid is a solid where particles are arranged irregularly, lacking any long-range order. The structure resembles that of supercooled liquids with only short-range order among particles.
Amorphous solids do not form a definite lattice structure and are often called pseudo solids. Their nature is further discussed in Structure of Solids topics.
Difference Table
| Crystalline Solid | Amorphous Solid |
|---|---|
| Orderly, repeating arrangement of particles | Irregular, random arrangement of particles |
| Forms a definite crystal lattice | Does not form a true lattice |
| Exhibits long-range order | Shows only short-range order |
| Sharp and fixed melting point | Melts over a range of temperatures |
| Anisotropic in nature (properties change with direction) | Isotropic (properties same in all directions) |
| Clear, smooth cleavage planes when cut | Irregular, curved or uneven surfaces on cutting |
| Definite and characteristic heat of fusion | No definite heat of fusion |
| True solid | Pseudo solid (supercooled liquid) |
| High symmetry in shape | Lacks distinct symmetry |
| Well-defined faces and geometry | Irregular shapes and surfaces |
| Electrical and optical properties vary with direction | Electrical and optical properties do not change with direction |
| Slow diffusion of particles | Relatively faster diffusion than crystalline solids |
| Copper sulfate, NaCl, quartz, diamond (examples) | Glass, rubber, plastic, pitch (examples) |
| Generally more hard and brittle | Usually softer and more flexible |
| Exhibits definite enthalpy of fusion | Does not show a definite enthalpy of fusion |
| Undergoes cleavage cleanly along planes | Breaks into irregular fragments |
| Crystalline structure is stable | Structure is less stable, may flow slowly |
| Regular thermal expansion | Thermal expansion is irregular |
| Has a specific and unique refractive index | May have variable refractive index |
| Used in precise optical and electronic applications | Used in applications requiring flexibility or moldability |
Key Differences
- Crystalline solids have long-range order, amorphous have short-range order
- Crystalline solids melt sharply, amorphous melt gradually
- Cleavage planes are smooth in crystalline, irregular in amorphous
- Anisotropy occurs in crystalline, isotropy in amorphous solids
- Crystalline shapes are regular, amorphous shapes are irregular
Examples
Common examples of crystalline solids are sodium chloride (NaCl), diamond, and quartz. These can be compared under the Properties of Solids for better conceptual clarity.
Glass, plastic, and rubber are typical examples of amorphous solids. For instance, glass windows and plastic containers are used daily.
Applications
- Crystalline solids: used in electronics, jewelry, and precise optics
- Amorphous solids: used in glassware, plastics, and synthetic rubbers
- Crystals are important for scientific instruments and sensors
- Amorphous materials suitable for flexible packaging and fibers
One-Line Summary
In simple words, crystalline solid has a definite, repeating atomic arrangement, whereas amorphous solid has an irregular and disordered structure.
FAQs on What Is the Difference Between Crystalline and Amorphous Solids?
1. What is the difference between crystalline solid and amorphous solid?
Crystalline solids and amorphous solids differ in their structure, melting points, and properties.
- Crystalline solids have a regular and repeating arrangement of particles, forming a definite geometrical shape.
- Amorphous solids have an irregular arrangement of particles and do not possess a definite shape.
- Crystalline solids possess a definite melting point, while amorphous solids soften gradually over a range of temperatures.
- Examples of crystalline solids: Sodium chloride, diamond, quartz.
- Examples of amorphous solids: Glass, plastic, rubber.
2. Define crystalline solids with examples.
Crystalline solids are solids in which particles are arranged in a regular, repeating three-dimensional pattern called a crystal lattice.
- They show a sharp, definite melting point.
- They have long-range order.
- Examples: Table salt (NaCl), quartz (SiO₂), diamond, sugar.
3. What are amorphous solids? Give two examples.
Amorphous solids are solids whose particles are arranged randomly, lacking a regular crystal lattice.
- They do not have a sharp melting point and soften over a range of temperatures.
- They possess only short-range order.
- Examples: Glass, plastic, rubber.
4. How do crystalline and amorphous solids differ in melting point?
Crystalline solids have a definite and sharp melting point, while amorphous solids melt gradually over a range of temperatures.
- Crystalline solids melt at a fixed temperature because of their regular lattice structure.
- Amorphous solids, lacking regular structure, soften when heated and do not have a fixed melting point.
5. Why is glass considered an amorphous solid?
Glass is considered an amorphous solid because its particles do not form a regular or repeating pattern and it does not have a definite melting point.
- The structure of glass is disordered, similar to liquids, but is rigid like solids at room temperature.
- It softens gradually when heated instead of melting sharply.
6. List two differences between crystalline solids and amorphous solids.
Crystalline solids and amorphous solids differ in structure and melting point.
- Crystalline solids have a regular arrangement and a definite melting point.
- Amorphous solids have an irregular arrangement and do not have a definite melting point.
7. Can amorphous solids be called supercooled liquids? Explain.
Amorphous solids can be called supercooled liquids because they have no fixed arrangement of particles and show some flow, although very slowly.
- They possess properties similar to liquids, such as lack of sharp melting point and ability to flow slowly under stress.
- This is why materials like glass are sometimes referred to as supercooled liquids.
8. Name any two properties that distinguish crystalline and amorphous solids.
Crystalline solids and amorphous solids can be distinguished by:
- Structure: Crystalline solids have a regular arrangement; amorphous solids have irregular arrangement.
- Melting Point: Crystalline solids have definite melting points; amorphous solids do not.
9. Is plastic a crystalline or amorphous solid?
Plastic is mainly an amorphous solid, as it has an irregular particle arrangement and does not display a sharp melting point.
10. What happens when amorphous solids are heated?
Amorphous solids soften and gradually flow or deform when heated, instead of melting abruptly like crystalline solids.
- The lack of long-range order causes them to behave like supercooled liquids upon heating.
