Answer to Question #76721 in Physical Chemistry for fardin

Question

Discuss the charecteristics of solids and their classification.

Answer 1

Answer: Solids, in contrast to liquids and gases, are characterized by the most ordering of the structure along the structural elements, that is, the solid-forming elements are arranged in order in such a way that the action from one end of the solid finds the same response at the other end. The entropy of a solid is low due to order. The elements are "rigidly" fixed and oscillate with respect to the fixed state.
Solid bodies are classified as follows:
1. According to the structural state:
- amorphous state. It is characterized by an unordered, but "rigidly fixed state" of atoms and molecules. The transition to a liquid state occurs gradually;
- crystalline state. Atoms or molecules are in an ordered state, forming a crystalline cell, the repetition of which (translation operations) produces a crystal. Distinguish polycrystalline and single crystal. Polycrystals are formed by small crystals interconnected by intermolecular forces. The single crystal is anisotropic;
- nanodispersed state. The state when the particle size of a solid is commensurable with the dimensions of the molecules.
2. By type of chemical bond:
- ionic crystals. Crystals in which the ionic bond is. Opposite-charged ions have an electron configuration of completed shells due to the localization of electrons;
- covalent crystals. The bond in such crystals is realized between atoms with a similar electronegativity. The formation of a connection goes through the socialization of electrons, when each atom puts into communication one electron each;
- metal crystals. They are formed by the socialization of the electrons of all atoms, that is, they are characterized by the existence of the so-called "electron gas";
- molecular crystals (crystals with van der Waals bond). Interaction occurs with the condensation, for example, of inert gases, methane, carbon dioxide and so on. The interaction is formed by directing the dipole moments of neighboring molecules, as a result of which the motion is coordinated, and a bond is formed;
- crystals with hydrogen bonds. These are crystals formed by condensation with the simultaneous formation of a hydrogen bond between the hydrogen atom of one molecule and the atom of the other molecule that is very different in electronegativity (usually oxygen, fluorine, sulfur).