Amorphous Solids

 Amorphous Solids 

Amorphous solids are rigid structures but they lack a well-defined shape. They do not have a geometric shape. So they are non crystalline. This is why they do not have edges like crystals do. In non crystalline solid, the atoms and molecules are not organized in a definite lattice pattern. The most common example of an amorphous solid is Glass. Gels, plastics, various polymers, wax, thin films are also good examples of amorphous solids.

Solids and liquids are both forms of condensed matter; both are composed of atoms in close proximity to each other. But their properties are, of course, enormously different. While a solid material has both a well-defined volume and a well-defined shape, a liquid has a well-defined volume but a shape that depends on the shape of the container.

Amorphous solids
Amorphous Solids

Stated differently, a solid exhibits resistance to shear stress while a liquid does not. Externally applied forces can twist or bend or distort a solid’s shape, but (provided the forces have not exceeded the solid’s elastic limit) it “springs back” to its original shape when the forces are removed. A liquid flows under the action of an external force; it does not hold its shape. These macroscopic characteristics constitute the essential distinctions: a liquid flows, lacks a definite shape (though its volume is definite), and cannot withstand a shear stress; a solid does not flow, has a definite shape, and exhibit elastic stiffness against shear stress.

On an atomic level, these macroscopic distinctions arise from a basic difference in the nature of the atomic motion. it contains schematic representations of atomic movements in a liquid and a solid. Atoms in a solid are not mobile. Each atom stays close to one point in space, although the atom is not stationary but instead oscillates rapidly about this fixed point (the higher the temperature, the faster it oscillates).

The fixed point can be viewed as a time-averaged center of gravity of the rapidly jiggling atom. The spatial arrangement of these fixed points constitutes the solid’s durable atomic-scale structure. In contrast, a liquid possesses no enduring arrangement of atoms. Atoms in a liquid are mobile and continually wander throughout the material.

This variation in characteristics of solids occurs due to the arrangement of their molecules. Here the particles of matter do not form the three-dimensional lattice structure that we see in solids. Some naturally occurring amorphous solids have impurities that prevent such a structure from forming. So they have a short order arrangement of molecules. Amorphous solids break into uneven pieces with irregular edges. And they do not have any distinct arrangement or shape of molecules. so they cannot be identified by their structure easy crystals.

Difference Between Crystalline and Amorphous Solids  

1. Crystals have an orderly arrangement of their constituent particles. In comparison, amorphous solids have no such arrangement. Their particles are randomly organized. 

2. Crystals have a specific geometric shape with definite edges. Amorphous solids have no geometry in their shapes. 

3. Crystalline solids have a sharp melting point on which they will definitely melt. An amorphous solid will have a range of temperature over which it will melt, but no definite temperature as such 

4. Crystals have a long order arrangement of their particles. This means the particles will show the same arrangement indefinitely. Amorphous solids have a short order arrangement. Their particles show a lot of variety in their arrangement.

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