There are three basic states of matter, they are solid, liquid, and gas. They are classified based on their structure of molecules, ions, and atoms that are arranged in proper order or scattered. Solids can further based on their crystal structure can be classified into crystalline and amorphous. Both of these solids can be differentiated based on their chemical and physical properties.
Crystalline vs Amorphous
The main difference between crystalline and amorphous is their structure. While crystalline have a more fixed shape and the ions are arranged in a particular pattern known as crystal lattice. However, in the case of amorphous, the molecules within the solid are scattered and not arranged in any particular order.
Comparison Table Between Crystalline and Amorphous
| Parameter of Comparison | Crystalline | Amorphous |
| Structure | Regular patterned ions | Random patterned ions |
| Melting Point | Fixed melting temperature | Not fixed melting temperature |
| Physical Properties | Anisotropic | Isotropic |
| Symmetry | Symmetrical | Unsymmetrical |
| Example | Quartz | Glass |
What is Crystalline?
Crystalline solid also denoted as a crystal is a solid material that is made up of atoms or ions that are arranged in an ordered microscopic structure that further forms the crystal lattice which spreads in all directions. All crystalline solids have a fixed melting point. The arrangement of atoms within a crystal is known as crystal structure. The atoms form a periodic arrangement. Although not all solids are crystals.
The crystal structure is featured by its unit cells. The unit cells are then further stacked into a three-dimensional format to create a crystal. Crystals are usually recognized by their distinct shape which consists of a flat surface along with sharp angles. It is difficult to differentiate between a crystalline and a non-crystalline by just feeling or looking at them. They can be differentiated based on their chemical and physical properties.
The crystalline solid requires extreme temperature to break down its intermolecular force. They have a fixed boiling and melting point as they have a uniform arrangement of molecules. Although when they are cut in any particular direction the physical properties change and hence it is known as anisotropic.
On certain occasion’scrystalline solid results in an amorphous based on its cooling process. For example, quartz is a crystal with oxygen and silicon atoms in an arranged form, but when cooled it can result in an A structured glass. Often the process of crystalline is avoided to receive amorphous solid as the final product for industrial purposes.
Crystals further can be grouped into 7 different types based on lattices and lines namely tetragonal, hexagonal, orthorhombic, trigonal, triclinic, cubic, and monoclinic. Crystalline solid is also defined by the kind of particles they are made up of and their chemical bonding. Based on that crystalline solid can b of 4 kinds ionic, covalent, metallic, and molecular.
What is Amorphous?
Amorphous has been derived from a Greek term meaning “shapeless”. They have irregular arrangements of constituent particles of solid. These blocks are similar to the basic structural unit that is found in the corresponding crystalline phase of a similar compound.
Theamorphous solid lacks a proper three-dimensional long-range order of crystalline material. The substance can be either solid or liquid depending upon the connectivity between the elementary building blocks. The solids have a high level of connectivity whereas the liquids have a low level of connectivity.
Amorphous solid does not have a fixed melting point and transformation of solid to liquid can happen over various temperature ranges. Amorphous solid are generally isotropic (perform uniform properties in all directions).
Any crystalline solid can be made amorphous by the process of rapid cooling. They do not allow their particles to be arranged in crystalline format. An amorphous solid can be transformed back into a crystalline solid it is left for a longer period below its melting point. The internal structure of the amorphous substance is created of interconnected structural blocks, they have a similar resemblance to crystalline material.
Amorphous solid consists of both natural and manmade substances. The most common example of Amorphous that is noticed is glass. Few other amorphous solid are film lubricants, metallic glasses, polymers, and gels. If the liquid phase is cooled quickly any material can solidify into an amorphous solid.
Main Differences Between Crystalline and Amorphous
- Crystalline solid are extremely structure in nature the molecules within the solid are organized in an arranged pattern is also known as crystal lattice. Amorphous solid on the other hand are not at all structured the molecules within the solid are in an unorganized manner.
- The crystalline solid has a fixed melting point but the amorphous solid does not have any fixed melting point. They melt over various temperatures.
- Crystalline solids are anisotropic whereas amorphous solids areisotropic.
- Crystalline solid is symmetrical in nature whereas amorphous solid is unsymmetrical in nature.
- An example of Crystalline is quartz and an example of amorphous is glass.
Conclusion
There are three states of matter namely solids, liquids, and gas. It all is depended on the factor of how closely or how far apart the molecules are packed from each other. Solids further are divided into two broad types namely crystalline and amorphous. They can be differentiated from each other based on structure, melting point, physical property, and symmetry.
Crystalline solids have a definite shape and structure. The molecules within the solid are arranged in a particular pattern. They have a fixed melting point. The crystallineis anisotropic. Amorphous on the other hand is also known as pseudo solids. The molecules within are not arranged in any pattern or format. They have various melting points. They are of irregular shape.
References
- https://www.sciencedirect.com/science/article/pii/S0169409X01000977
- https://books.google.com/books?hl=en&lr=&id=Pl1b_yhKH-YC&oi=fnd&pg=PP1&dq=crystalline&ots=d7r_cEFX-f&sig=yfunsduS0YhIFEujbVKyNyTgUKc
- https://www.tandfonline.com/doi/abs/10.1080/00018738600101911
- https://aip.scitation.org/doi/abs/10.1063/1.1659873