📚 Lesson Notes - Read Carefully!
🧪 Particle Theory
All matter is made up of tiny particles (atoms and molecules). These particles are always moving, and the speed and arrangement of these particles determines the state of matter.
💡 Key Idea: The three states of matter are SOLID, LIQUID, and GAS. The difference between them is how the particles are arranged and how much they move!
❄️ Solids
- Arrangement: Particles are packed very close together in a regular pattern
- Movement: Particles vibrate in fixed positions but cannot move around
- Properties: Fixed shape, fixed volume, cannot be compressed
- Example: Ice, metal, wood
💧 Liquids
- Arrangement: Particles are close together but randomly arranged
- Movement: Particles can slide past each other and move around
- Properties: No fixed shape (takes shape of container), fixed volume, cannot be compressed
- Example: Water, juice, oil
💨 Gases
- Arrangement: Particles are very far apart with no regular pattern
- Movement: Particles move very fast in all directions
- Properties: No fixed shape, no fixed volume, CAN be compressed
- Example: Air, steam, carbon dioxide
🌡️ Temperature Connection: When you heat a substance, particles gain energy and move faster. When you cool it, particles lose energy and move slower.
🔄 Changes of State
When substances change state, the particles stay the same but their arrangement and movement changes:
- Melting: Solid → Liquid (heating, particles gain energy)
- Freezing: Liquid → Solid (cooling, particles lose energy)
- Boiling/Evaporation: Liquid → Gas (heating, particles escape)
- Condensation: Gas → Liquid (cooling, particles slow down)
- Sublimation: Solid → Gas directly (like dry ice!)
🔥 Important: During a change of state, the temperature stays constant! All the energy goes into breaking or forming bonds between particles.
🔗 Chemical Bonding
Atoms join together by forming bonds. There are different types of bonding:
⚡ Ionic Bonding
- Happens between metals and non-metals
- Electrons are transferred from metal to non-metal
- Creates charged ions (positive metal ions, negative non-metal ions)
- Opposite charges attract and form a strong bond
- Properties: High melting point, conducts electricity when molten or dissolved, forms crystals
- Examples: Sodium chloride (NaCl - table salt), Magnesium oxide (MgO)
🤝 Covalent Bonding
- Happens between non-metals only
- Electrons are shared between atoms
- Forms molecules
- Properties: Low melting point, does NOT conduct electricity, can be solid/liquid/gas
- Examples: Water (H₂O), Carbon dioxide (CO₂), Methane (CH₄)
🏗️ Metallic Bonding
- Happens in metals only
- Metal atoms lose electrons to form positive ions
- Electrons move freely between ions ("sea of electrons")
- Properties: High melting point, conducts electricity, malleable (can be hammered), ductile (can be stretched)
- Examples: Copper, iron, aluminum
🎯 Quick Memory Trick:
Ionic = Ions (transfer electrons)
Covalent = Comfy sharing (share electrons)
Metallic = Moveable electrons (sea of electrons)
📊 Key Differences Summary
Ionic: Metal + Non-metal → Transfer → High MP → Conducts when liquid
Covalent: Non-metal + Non-metal → Share → Low MP → Doesn't conduct
Metallic: Metal atoms → Free electrons → High MP → Always conducts
⚠️ Ready for the exam? Make sure you understand:
✓ How particles behave in each state
✓ What happens during changes of state
✓ The three types of bonding and their properties
✓ Which elements form which types of bonds