What is the classification of crystals?

Types of crystals are categorized as: ionic crystals, atomic crystals, molecular crystals, and metal crystals.

Ionic crystals

Crystals made of cations and anions bonded by ionic bonds.

Common ionic crystals: strong bases, active metal oxides, most salts.

Atomic crystals

Crystals in which all the atoms are bonded by *** valence bonds in a spatial mesh.

Characteristics of atomic crystals: Because of the high *** valence bonding energy, atomic crystals generally have high melting and boiling points and great hardness, and are generally non-conductive and insoluble in common solvents.

Common atomic crystals: diamond, monocrystalline silicon, silicon carbide (adamantine), silicon dioxide, boron nitride (BN) and so on.

Characteristics

(1) Naturally condensed crystals formed without external interference possess a neat and regular geometrical shape, i.e., the self-paradigm of the crystal.

(2) Crystals have a fixed melting point and the temperature remains constant throughout the melting process.

(3) Single crystals are characterized by anisotropy.

(4) Crystals allow regular diffraction of X-rays.

The macroscopic ability to produce X-ray diffraction phenomena is the main method of experimentally determining whether a substance is a crystal or not.