Physical Chemistry – The Solid State-Type of Crystalline Solid- Ionic – Covalent – Metallic – part-3.

Physical Chemistry – The Solid State-Type of Crystalline Solid- Ionic – Covalent – Metallic – part-3.

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 Physical Chemistry – The Solid State

Types of Crystalline Solids: Ionic, Covalent, Metallic (Part-3)

Crystalline solids are highly ordered structures where atoms, ions, or molecules are arranged in a regular, repeating pattern. These solids can be classified into different types based on the forces holding them together.

 1. Ionic Crystals (Ionic Solids)

Constituent Particles: Ions (Cations & Anions)
Bonding Force: Electrostatic forces (Ionic bonds)
Examples: NaCl (Salt), KCl, CaF₂, MgO

 Properties of Ionic Solids

High Melting & Boiling Points (Strong electrostatic forces)
Hard & Brittle (Ions are in fixed positions, break under stress)
Soluble in Water (Dissociates into ions)
Conducts Electricity in Molten/Aqueous Form (Ions move freely in solution)

Example: Sodium chloride (NaCl) forms a cubic lattice where Na⁺ and Cl⁻ ions are held by strong electrostatic forces.

 2. Covalent or Network Crystals 

Constituent Particles: Atoms
Bonding Force: Covalent Bonds (Strongest bond type)
Examples: Diamond (C), Graphite (C), SiO₂ (Quartz), SiC

 Properties of Covalent Solids

Extremely Hard & Brittle (Due to strong covalent bonding)
Very High Melting Points (Breaking covalent bonds requires a lot of energy)
Non-Conductors of Electricity (No free electrons, except graphite)
Insoluble in Water

Example: Diamond has a 3D tetrahedral network of carbon atoms, making it the hardest natural substance. In contrast, graphite has layered hexagonal sheets that slide over each other, making it a good lubricant & conductor.

 3. Metallic Crystals (Metallic Solids) 

Constituent Particles: Metal Atoms
Bonding Force: Metallic Bonds (Electron Sea Model)
Examples: Fe (Iron), Cu (Copper), Al (Aluminum), Ag (Silver)

 Properties of Metallic Solids

Good Conductors of Electricity & Heat (Free-moving electrons)
Malleable & Ductile (Layers of atoms slide over each other)
Lustrous (Shiny) (Light reflection from free electrons)
Variable Melting & Boiling Points (Depends on metal type)

Example: Copper (Cu) is used in wires due to its high conductivity and malleability.

 Summary Table of Crystalline Solids

Type of Solid	Forces of Attraction	Properties	Examples
Ionic Solids	Electrostatic Forces	Hard, Brittle, High MP, Conductive in liquid state	NaCl, KCl, MgO
Covalent Solids	Covalent Bonds	Very Hard, High MP, Non-Conductive (except graphite)	Diamond, Quartz, Graphite
Metallic Solids	Metallic Bonds	Conductive, Malleable, Ductile, Lustrous	Fe, Cu, Ag

 Conclusion

Understanding ionic, covalent, and metallic solids helps in predicting properties like hardness, conductivity, and solubility. These concepts are fundamental in chemistry, material science, and engineering.

 Got any questions about crystalline solids? Let me know!

Physical Chemistry – The Solid State-Type of Crystalline Solid- Ionic – Covalent – Metallic – part-3.

II Inorganic Chemistry Sem- IV Chapter -3. Ionic Solids

PHYSICAL CHEMISTRY – [THE SOLID STATE – B.Sc

The Crystalline Solid State

The Solid Stat The Solid State