C2 - Bonding, Structure and The properties of Matter

• What are the three types of strong chemical bonds?

  Ionic, covalent, and metallic
• How would you describe an ionic bond?

  Strong electrostatic attractions between oppositely charged ions
• How does an ionic bond form?

  A metal atom loses electrons to a non-metal
• How can you show the formation of an ionic bond diagrammatically?

  Using a dot and cross diagram
• How do the charges on ions relate to the periodic table?

  Group 1 & 2 form 1+ and 2+ ions
• How can the structure of sodium chloride be represented?

  As a giant ionic lattice compound
• Why do ionic compounds have high melting and boiling points?

  Due to strong electrostatic attractions in all directions
• Why can ionic compounds conduct electricity when molten or dissolved?

  Because the ions are free to move
• How does a covalent bond form?

  Two non-metal atoms share a pair of electrons
• Name some common simple covalent molecules.

  O₂, CO₂, NH₃, H₂O, N₂
• How can covalent molecules be represented diagrammatically?

  Using Lewis structures or molecular models
• Why do small molecular substances usually have low melting and boiling points?

  Weak intermolecular forces are overcome easily
• Why do larger molecules have higher melting and boiling points?

  Intermolecular forces increase with size
• Why do simple molecular substances NOT conduct electricity?

  Because the molecules have no overall electric charge
• How are atoms within a polymer linked?

  By many strong covalent bonds
• How can polymers be represented diagrammatically?

  Using repeating unit structures
• Why are polymers solid at room temperature?

  Due to strong covalent bonds in their structure
• What are some properties of giant covalent structures?

  High melting points and hardness
• Why do giant covalent structures have high melting points?

  All atoms are linked by strong covalent bonds
• Give examples of giant covalently bonded structures.

  Diamond, graphite, and silicon dioxide
• In diamond, how many covalent bonds does each carbon form?

  Four covalent bonds
• What are some properties of diamond related to its structure?

  Very hard, high melting point, non-conductor
• In graphite, how many covalent bonds does each carbon form?

  Three covalent bonds
• Why do the layers of graphite rub off easily?

  Weak forces between the layers allow movement
• What happens to the 4th electron from every carbon atom in graphite?

  It becomes delocalised, allowing conductivity
• What is graphene?

  A single layer of graphite
• Why is graphite useful in electronics?

  Delocalised electrons allow it to conduct electricity
• What is a fullerene?

  Molecules of carbon atoms with hollow shapes
• How many carbons are there in the rings of atoms in a fullerene?

  Mostly hexagonal rings, some have 5 or 7
• What shape is Buckminsterfullerene (C₆₀)?

  Soccer ball shape
• What are carbon nanotubes?

  Cylindrical fullerenes with high length to diameter ratios
• Give some properties of carbon nanotubes.

  Strong, light, and conduct electricity
• What are carbon nanotubes used for?

  Nanotechnology and lightweight materials
• Describe the structure of a metal.

  Giant structures with strong metallic bonding
• What is metallic bonding?

  Delocalised electrons surround positive metal nuclei
• Why are metals able to be shaped and bent?

  Layers of positive nuclei can move relative to each other
• How are metals able to conduct heat and electricity?

  Delocalised electrons flow throughout the structure
• What is added to pure metals to make them harder?

  Other metals or carbon to produce alloys
• What makes alloys harder than pure metals?

  Differently sized nuclei make layers harder to distort
• What are the three states of matter?

  Solid, liquid, and gas