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The constituent particles of crystalline solids are arranged in a predictable and repeating pattern. The term “crystal lattice” refers to the diagrammatic arrangement of three-dimensional groupings of constituent particles in a crystal, in which every particle is represented as a point in space. The atoms in a crystal lattice are packed so closely together that there is hardly any room between them.
Close packing in solids
The effective arrangement of constituent particles in a crystal lattice in a vacuum is known as close packing in crystals, also known as close packing in solids. To further comprehend this set, we must suppose that all particles (atoms, molecules, and ions) share the same spherical solid form. Therefore, the unit cell of a lattice is a cubic shape. When we stack the spheres in the cell, there will still be a few open places. To minimise these empty areas, the arrangement of these spheres must be exceedingly effective. The spheres should be placed as closely together as possible to reduce vacant areas.
Close packing in crystalline solids in one dimension
One-dimensional close packing involves placing spheres in a row so that adjacent atoms are in close proximity to one another. The number of closest neighbours’ particles is the definition of the coordination number. When packed closely in one dimension, the coordination number is two.
Close packing in crystalline solids in two-dimension
A row of tightly packed spheres is piled to create a two-dimensional pattern in two-dimensional close packing. There are two ways to perform this stacking:
Square close packing: In a tight packing, the second row might be positioned directly beneath the first row. As a result, if the first row is referred to as a “A” type row, the second row, which is arranged exactly like the first one, is also a “A” type row. Each sphere in this configuration is in contact with four other spheres. As a result, it has a coordination number of 4. We notice that a square is created when the centres of the four closest neighbouring spheres are connected. Square close packing in two dimensions is the term used to describe this sort of packing in crystalline materials.
Hexagonal close packing: In order for the second row’s spheres to fit in the first row’s depressions, it can be arranged below the first row in a staggered fashion. As a result, the second row, which is structured differently, can be referred to as “B” type if we refer to the first row as an “A” type row. Once more, the third row displays in “A” type. The term “ABAB” type is used to describe this kind of packing. Each sphere in this configuration is in contact with six other spheres. Consequently, it has a coordination number of six. We note that a hexagon is created if the centres of the six nearby spheres are connected. In two dimensions, this kind of solid packing is referred to as hexagonal tight packing. Compared to square close packing, it has less empty space and is therefore more efficient when packing.
Conclusion
The constituent particles (atoms, ions, or molecules) are intricately entangled during the crystallisation process. A closely packed arrangement is one in which the lowest amount of empty space is left while the largest amount of space is used. This is consistent with the scenario of the highest density conceivable. The stability of the packed system is higher the closer the packing.
Most of the solids we encounter are crystal solids. These crystalline formations emerge from the precise configuration of constituent particles known as crystal lattices. These forms are brought about by the close packing of their atoms.
