State of Matter Solid

Introduction

• Document Title: Foundation in Science

• Module: Chemistry 3

• Topic: State of Matter - Solid

• Prepared by: Siti Fatimah binti Mohammad Yaacob

• Motto: Inspire • Empower • Elevate

Learning Outcomes

1. Understanding lattice structures of crystalline solids:

   • Giant ionic (e.g., Sodium Chloride, Magnesium Oxide)

   • Simple molecular (e.g., Iodine, Ice)

   • Giant molecular (e.g., Silicon(IV) Oxide, Graphite, Diamond)

   • Giant metallic (e.g., Copper)

2. Effects of structure and bonding on physical properties:

   • Melting point

   • Boiling point

   • Electrical conductivity

   • Solubility

3. Deducing structure and bonding from given information.

Bonding and Structure

• All matter consists of particles:

  • Atoms

  • Molecules (groups of atoms held by covalent bonds)

  • Ions (charged atoms or molecules)

• Bonding Types:

  1. Ionic - Attraction between oppositely charged ions

  2. Metallic - Attraction between same electropositive atoms

  3. Covalent - Electrons shared between atoms

  4. Intermolecular Forces (IMF) - Attraction between small molecules (e.g., Van der Waals forces or Hydrogen Bonds)

Types of Solid

Crystalline vs Amorphous

• Crystalline Solids: Well-arranged particles, crystal structure with an ordered arrangement.

• Amorphous Solids: Irregularly shaped particles, lack a defined form.

Crystalline Solid Structure

• Structure refers to how particles arrange themselves:

  • Crystal Lattice: Regular, repeating pattern in three dimensions.

  • Unit Cell: Smallest portion of crystal lattice indicating three-dimensional pattern.

Types of Crystalline Solid Structures

1. Giant Ionic Lattice Structure (e.g., NaCl, MgO)

2. Giant Metallic Lattice Structure (e.g., Copper)

3. Simple Molecular Lattice Structure (e.g., Iodine(s), Ice)

4. Giant Covalent Lattice Structure (e.g., Diamond, Graphite)

Giant Ionic Solid

Structure

• Giant ionic structures form a lattice through ionic bonds, with anions and cations arranged in 3D.

Examples

• Sodium Chloride (NaCl): Na+:Cl- ratio 1:1

• Magnesium Oxide (MgO): Mg2+:O2- ratio 1:1

• Aluminum Oxide (Al2O3): Al3+:O2- ratio 2:3

Physical Properties

1. Hard and Brittle: Strong ionic forces make it hard, but crystal shatters under force due to displacement of like-charged ions.

2. Solubility: Soluble in polar solvents (e.g. water), but insoluble in non-polar solvents (e.g. ether).

3. High Melting and Boiling Points: Strong electrostatic forces require significant energy to break. Examples:

   • NaCl: 801°C (melting), 1465°C (boiling)

   • MgO: 2850°C (melting), 3600°C (boiling)

4. Electrical Conductivity: Conducts electricity when molten or dissolved due to free movement of ions, but not in solid form.

Giant Metallic Solid

Structure

• Cations in a 3D lattice with delocalized valence electrons.

Physical Properties

1. Good Electrical and Heat Conductivity: Delocalized electrons allow current flow in solid and liquid states.

2. Relatively High Melting and Boiling Points: Proportional to strength of metallic bonding affected by:

   • Number of valence electrons

   • Size of cations

3. Mechanical Properties: Typically soft, malleable, and ductile due to non-directional bonding.

4. Solubility: Metals are generally insoluble in water and organic solvents.

Simple Molecular Solid

Structure

• Comprised of small covalent molecules held by weak intermolecular forces.

Physical Properties

1. Low Melting and Boiling Points: Mostly determined by weak IMF.

2. Mechanical Properties: Soft, crumbly, and not very strong due to weak forces.

3. Electrical Conductivity: Generally poor since no free-moving ions exist.

4. Solubility: Solubility is "like dissolves like"; non-polar molecules dissolve in non-polar solvents.

Giant Covalent Solid

Structure and Allotropes of Carbon

• Forms through a network of covalent bonds.

Diamond

• Bonding: Each carbon atom forms four covalent bonds, creating a strong tetrahedral structure.

• Properties: Very hard, high melting point, electrical insulator, insoluble.

Graphite

• Bonding: Each carbon forms three bonds in hexagonal layers, allowing for free-moving electrons.

• Properties: Conducts electricity, soft and slippery, high melting point, insoluble.

Silicon(IV) Oxide

• Similar properties to diamond. Each silicon bonded to four oxygen atoms in tetrahedral arrangement, resulting in high melting point and hardness.

Summary of Crystalline Solids

1. Giant ionic lattice: Oppositely charged ions.

2. Giant metallic lattice: Metal cations and delocalized electrons.

3. Simple molecular lattice: Individual molecules and intermolecular forces.

4. Giant covalent lattice: One giant molecule held by covalent bonds.

Questions

1. Explain differences in hardness between diamond and graphite.

2. Discuss density differences between graphite and diamond.

3. Address melting points of both substances despite their differing hardness.

4. Explain electrical conductivity variations.

5. Discuss solubility properties of both materials.