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Introduction
A solid material where components like atoms, molecules, or ions are organised in a definite and sequentially organised over a vast distance in the crystal lattice is called Crystalline Solids.
Crystalline Solids : Structure
Crystalline solids have definite sides and faces with specific melting points.The study of the geometrical structure in the crystal lattice is known as crystallography. In physics or chemistry Bragg diffraction experiment is useful for the determination and analysis of crystal structure. It is made from the simple relationship between the wavelengths of the x-ray radiation and spacing between the two lattice planes.
Crystalline Solids : Properties
The components in crystalline solids will be atoms, ions, molecules Crystalline solids have properties of high melting points, flat faces, and sharp sides. It is a well-defined form as it is organised regularly. Specific and the sequential organisation of the components expands over a vast distance in crystal lattices.
Crystalline solids in cubic class represent anisotropic properties. The extent of the anisotropic characteristics depends on the direction of structural calculation.
Types Of Crystalline Solids
These solids are classified into four types on the basis of the nature of bonding of component particles.
1. Molecular Solids
Molecules are the element particles in these solids. A weak Van der Waals force of attraction holds together these molecules.Because of the presence of weak forces, these solids are soft in nature. Molecular solids are bad conductors of electricity as there are no free electrons to use. Their melting and boiling points are also low, so they evaporate easily.
Molecular solids are divided into 3 classes as follows.
Polar Molecular Solids
Polar molecular solids have a polar covalent bond between their molecules. The polarity in their bond is developed because of the difference in the electronegativity of the atoms which contributes to bonding. Therefore, limited charges are developed on atoms that form a dipole-dipole interaction force and this force holds the solid together.
Non-Polar Molecular Solids
In Non Polar Molecular Solids, atoms/elements form the molecule, which is after joined by a nonpolar bond to form this kind of molecular solid. These solids have weak Van Der Waals forces, thus they are soft. No polarity is found in the bonds amid these solids as the same atoms or molecules are joined.
Hydrogen Bond Molecular Solids
When bonds are made with fluorine, oxygen, or nitrogen, for hydrogen it is known as a hydrogen bond. These are polar covalent bonds and are relatively strong bonds. The polarity in hydrogen bonds is developed because of the electronegativity difference between hydrogen and the other element, which could be N/O/F. The solids in which these types of bonds are present are known as hydrogen-bonded molecular solids.
2. Ionic Solids
Ionic solids are formed by ions. These ions are connected by the strong electrostatic forces of attraction in the solid. Ions are charged particles that are of two kinds- cations (positively charged) and anions (negatively charged). These ions are orderly organised in the ionic solid. The force of attraction acting between cations and anions is called an electrostatic force of attraction. These strong forces grant the hardness, fragile, and high melting points of these solids. These solids manage electricity only in a molten state/aqueous state.This is because in these states the ions are free to move, unlike solid-state where they are fixed.
3. Covalent Solids
Covalent solids are also known as network solids as they are formed by a severe network of covalent bonds present in their adjoining atoms forming the solid. The component atoms/elements are impartial atoms and can be the same as in diamonds and are also known as carborundum.
4. Metallic Solids
Metallic solids have fixed positive ions surrounded by free electrons in their structure.Because of these free electrons, metallic solids are good conductors of electricity and heat. In given metallic solids, there are positive ions present in the puddle of electrons. The melting and boiling points of metallic solids can range between moderate to high. These solids can be hard or soft.
Conclusion
Crystalline solids are the types of solid formed by atoms, ions, or molecules. Molecular, ionic, covalent, and metallic crystalline solid are the main components of crystals formed by their elements with a hard structure. Solids are hard because of the absence of transferring motion on the structural unit. These units are secure to their designated position with strong forces of attraction.
