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.

 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

 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

Here’s a concise and student-friendly explanation of Physical Chemistry – The Solid State (Part-3): Types of Crystalline Solids, covering Ionic, Covalent, and Metallic Solids, useful for CBSE, NEET, JEE, or general Chemistry learning.

The Solid State – Types of Crystalline Solids (Part-3)

Crystalline solids have definite shapes and patterns because their particles are arranged in an orderly three-dimensional pattern.

1. Ionic Solids

Definition:
Made of positive and negative ions held together by strong electrostatic forces of attraction.

Examples: NaCl (Sodium chloride), KBr, MgO

Properties:

• High melting and boiling points
• Hard and brittle
• Conduct electricity in molten or aqueous state (not in solid state)
• Soluble in water, not in organic solvents

Application Tip: Most salts are ionic solids.

2. Covalent (or Network) Solids

Definition:
Atoms are bonded by strong covalent bonds throughout the crystal in a network.

Examples: Diamond (C), Silicon carbide (SiC), Quartz (SiO₂)

Properties:

• Very hard and brittle (e.g., diamond is the hardest known substance)
• Extremely high melting points
• Do not conduct electricity (except graphite)
• Insoluble in all solvents

Special Case – Graphite:

• Though covalent, graphite conducts electricity due to free electrons (delocalized π-electrons) between layers.

3. Metallic Solids

Definition:
Made up of positive metal ions in a ‘sea’ of mobile electrons.

Examples: Fe, Cu, Ag, Al, Zn

Properties:

• Good conductors of heat and electricity
• Malleable and ductile
• Lustrous (shiny)
• Range of melting points

Application Tip: Most metals used in industry and electrical applications fall in this category.

Quick Comparison Table

Mnemonic to Remember – “I Can Make”

• I = Ionic
• C = Covalent
• M = Metallic

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

TYPES OF SOLIDS