Amorphous Solids

 The substances that appear like solids but do not have well developed perfectly ordered crystalline structure are called amorphous ( no form ) Solids. Tar, Glass, Plastic, Rubber, Butter etc. are classified as amorphous solids. Amorphous solids do not have ordered internal structure and do not melt at a definite, sharp melting point. With increase of temperature it gradually softens, becomes less viscous and melt over a range of temperature. Amorphous solids are not solids in real sense. Truely they are super cooled liquids. The regular arrangement of constituent particles is present only up to short distance in amorphous solids is similar to the structure of liquids. Amorphous solids behave like fluids and very showly float under gravity. Due to the property of liquids, fluidity, the lower sides of glass panes of windows, photoframes, cupboards and showcases become slightly thicker and upper ends become thinner. Amorphous solids are also called pseudo solids or super cooled  liquids. Like crystalline solids the values of physical properties of amorphous solids do not change with change of directions. The properties remain the same in all directions. Two dimensional structures of crystalline quartz and amorphous quartz glass.