Key Factors Determining Substance Properties

• Type of Particles
• Type of Bonding
• Arrangement of Particles

Type of Particles

Particles can be atoms, ions, or molecules. Ionic substances conduct electricity when melted or dissolved, and water solubility requires ions or polar molecules.

Type of Bonding

Bonding can be ionic, covalent, metallic, or involve weak intermolecular forces. Stronger bonds lead to higher melting/boiling points and hardness. Example: SiO₂ (strong covalent bonds) vs. CO₂ (weak intermolecular forces).

Arrangement of Particles

Particles can be arranged in planes, layers, or 3D networks, affecting properties like hardness and conductivity. Example: Graphite (2D layers) vs. Diamond (3D network).

Electrical Conductivity

• Ionic Compounds: Non-conductive in solid state but conductive when melted or dissolved.
• Acids: Conduct electricity when dissolved due to ionization.
• Metals: Good conductors due to free electrons.

Diamond Properties and Uses

Diamond is the hardest known material, used in ornaments, cutting tools, medical instruments, and audio equipment.

Graphite Properties and Uses

Graphite has a 2D layered structure with weak van der Waals forces between layers. It is used in refractory items, nuclear reactors, lubricants, and pencils.