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Most of the solids we find around ourselves are crystal solids. These crystalline shapes form due to the arrangement of constituent particles in a specific arrangement known as crystal lattices. These structures form due to close packing of their atoms. Let us study this in detail.

Close Packing in Crystal

Close packing in crystals refers to space efficient arrangement of constituent particles in a crystal lattice. To understand this packing more clearly we have to assume all particles (atoms, molecules and ions) are of the same spherical solid shape.

So the unit cell of a lattice is a cubic shape. Now when we stack spheres in the cell, there will always be some empty spaces. To minimize these empty spaces, the arrangement of these spheres must be very efficient. The spheres should be arranged as close together as possible to eliminate empty spaces.

Another related concept is that of Coordination Number. The coordination number is the number of atoms that surround a central atom in a crystal lattice arrangement. It is also known as Ligancy. So this close packaging of the constituent particles happens in three ways. Let us take a look at each of them.

Close Packing in Crystals