Difference Between Crystalline and Amorphous

Introduction

The fundamental states of matter in which the molecules are closely arranged or packed are solid. So there is a strong attractive force is present in the molecules of solids. Solid has a definite shape and structural rigidity compared to other states of matter. It will not flow or expand like other states gas and liquid. So in the case of solids rather than moving the position of atoms must be considered. The arrangement of these atoms in the solids is generally in two ways. The regular repeating and ordered arrangement of particles in the solids leads to the formation of Crystalline solids. While the disordered and irregular arrangement of atoms in the way that they form an aggregate leads to the formation of amorphous solids.

Classification of solids

Solids are categorized into two types. They are

• Crystalline solids

• Amorphous solids

The crystalline solids are further divided into,

• Crystalline solids

  • Ionic crystal

  • Covalent crystal

  • Molecular crystal

  • Atomic solids

  • Metallic crystals

Crystalline Solids

Crystals or also called crystalline solids are types of solids that possess a distinct internal structure. The arrangement of particles is in a way that the particles are arranged in an ordered fashion. So crystalline solids have a highly organized microscopic pattern in which it broadens in all directions. And the study of these structures is crystallography. Each structure present in crystalline solids gives a distinctive pattern when they are exposed to X-rays. The corresponding angles in the crystals do not depend on the size of the crystals instead it will depend on the regular arrangement of atoms in the solids. And this can be further used for the detection of unknown solid materials. The breaking of ionic crystals of this type leads to the formation of new crystals with the same intersecting angles as the parent crystal.

As crystalline solids are categorized further into some other categories and are based on the intermolecular force of attraction present on them. In molecular crystal van der Waal force is present. In an ionic crystal ionic bond is present. In covalent crystals covalent bond is present. In metallic crystal metallic bond is present. And in atomic solids, one atom is bonded to another forming a crystalline solid.

The crystal structure is distinguished by the unit cell, it is an imaginary box that consists of one or more atoms in a distinct spatial configuration. These unit cells combined to form the three-dimensional arrangement of crystals. These unit cells are packed in a way that there is no gap in between them. The regularity in the arrangement of atoms in crystals will leads to sharp melting and boiling points. That is the intermolecular forces present in between the atoms of solids are all same and similar energy is required for the cleavage of these molecules. Examples of solids having a crystal structure are Diamond, table salts, ice, quartz, mica, alum, calcium fluoride, etc. The arrangement of atoms in the crystals is shown in the below figure.

Properties

Some of the important properties of crystalline solids are discussed in detail in the below points.

• They have long-range orders.

• They have a sharp melting point.

• Regular arrangements are present.

• They are anisotropic which means they possess different properties in different directions.

• Has three-dimensional geometry.

• Possess a rigid structure.

• Can be broken to smooth surfaces.

• Has a constant value of heat of fusion.

Amorphous Solids

The noncrystalline solids are provided with the name amorphous solids. The atoms and molecules in these solids are not arranged in a definite pattern or regular fashion. It lacks the ordered internal structure of crystalline solids. When they undergo a cleavage it will not be in an ordered manner and will not follow the regular arrangement. Their properties will also vary with the varying position since their arrangement of atoms is in different positions. Glass is a well-known commonly known example of amorphous solids in which the arrangement of atoms is irregular. This is the reason why they break does not follow any order that is fragments of different shapes will be obtained upon breaking. Glass may look like a crystal but the internal arrangement of this substance is very different. They are also called supercooled liquids.

Amorphous solids somewhat look like liquids. As their atoms are not arranged in an ordered manner there is no definite shape for this substance they are more like liquids. It is also given the name pseudo solids because of its liquid-like properties. That is why glass flow, the windows made up of glass become thicker at the lowest portion.

The properties of amorphous solids are also different it doesn't possess any sharp melting and boiling points. And the physical properties are the same in all directions that is they are isotropic This is because the atoms combine to to to aggregate. Plastics, rubber, glasses, gels, polymers, wax, lubricants, etc. are amorphous solids.

Properties

Some of the important properties of amorphous solids are discussed in the below points.

• They possess a short-range rider.

• Does not have a sharp melting point.

• Amorphous solids when heated at high temperature get converted to glass-like material having similarity to crystals.

• It doesn't have definite heat of fusion.

• They are isotropic that is they possess the same properties in all directions.

• It can be converted to a crystalline form.

• They are high viscous supercooled liquids in the form of solid.

Difference Between Crystalline Solid and Amorphous Solid

Crystalline and amorphous solids are two types of solids with different properties. So they are entirely different materials even though they are solids. Some of the differences between these two solids are tabulated in the following table.

Crystalline solids	Amorphous solids
An order arrangement is present.	No such ordered arrangement is present.
It possesses a pointed melting point.	No pointed melting point.
Anisotropic in nature.	Isotropic in nature.
Long-range order is present.	Only short-range orders.
Contains covalent, ionic, van der Waals interaction, and metallic bond.	Contains only covalent bonds.
Has a sharp heat of fusion point.	No sharp heat of fusion point.
Pseudo Solids.	True solids.
Symmetrical in nature.	Unsymmetrical in nature.
Has a definite shape.	No definite shape.
Sodium chloride, Diamond, quartz, etc are examples.	Glass, polymers, wax, etc are examples.

Conclusion

Solids are a chemical state in which the particles are arranged in a way that one atom lies next to another. They possess a definite shape and size. And doesn't varies with any external pressure. The solids are normally of two types Crystalline and Amorphous Solids. The solid in which the atoms possess a three-dimensional geometry formed by the regular periodic arrangement of particles or atoms in crystalline solids. While the one that doesn't contain any regular arrangement or order is amorphous solids. Amorphous solids are pseudo solids while those crystalline solids are true solids. Glass is an example of amorphous solids. While the diamond is an example of crystalline solids.

FAQs

1. Give an example of an ionic crystal?

As ionic crystals contain ionic bonds. Examples of ionic crystals are Sodium chloride, Sodium fluoride, Potassium chloride, etc.

2. Is diamond an ionic crystal?

Diamond is an allotrope of carbon in which carbon atoms are covalently arranged forming a tetrahedral so it is a covalent crystal, not an ionic crystal.

3. Is quartz an ionic crystal?

Quartz is also a covalent crystal in which the atoms are bonded together to form covalent bonds.

4. Do amorphous solids soften when heated?

Amorphous solids when heated over a range of temperatures soften. And is because the stronger attraction forces present on them get broken upon heating.

5. Why do amorphous solids not have a long range?

Amorphous solids are formed by rapid cooling. So they do not contain enough particles in them. And they connect with the nearest particles only. So they have short-range orders.