The molecular structure of solids determines its basic properties: hardness, elasticity, shape retention under normal conditions, plasticity.
Solids can be crystalline and amorphous at the molecular level. In both cases, their molecules are in vibrational motion around the equilibrium position at the sites of the molecular lattice.
Only in a crystalline body does this lattice have an orderliness throughout the body (a substance that has a certain volume, shape), in any direction.
In the amorphous, however, there is no extended ordering, the lattice nodes are located chaotically, relative to each other.
In any of these cases, the presence of a similar molecular structure allows a solid to be solid, to maintain its shape (the forces of mutual attraction of molecules at the nodes of the molecular lattice are very large and firmly hold them in their places, allowing only, as mentioned above, vibrational chaotic movements relative to their holding centers).
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