Chem unit 2

• What is metallic bonding?

  When metal atoms bond together
• What type of structure do metals have?

  Giant structures of regularly arranged atoms
• What does it mean for electrons to be delocalised?

  They are free to move through the structure
• How are strong metallic bonds formed?

  By sharing delocalised electrons
• What causes the strength of a metallic bond?

  The attraction between metal ions and delocalised electrons
• What property allows metals to conduct electricity?

  Delocalised electrons carry electrical charge
• How do metals conduct heat?

  Delocalised electrons and closely packed ions transmit energy
• What are the characteristics of metals regarding malleability and ductility?

  They are malleable and ductile
• Why do metals have high melting and boiling points?

  Strong metallic bonds require large amounts of energy to break
• How do melting and boiling points change across a period in the Periodic table?

  They increase due to more delocalised electrons
• What is an ion?

  A charged particle with different protons and electrons
• What is a positive ion?

  More protons than electrons
• What is a negative ion?

  More electrons than protons
• What is ionic bonding?

  Bonding between metal and non-metal atoms
• How do ionic bonds form?

  Atoms transfer electrons to achieve full outer shells
• What is a Dot and Cross diagram?

  A representation to show ionic bonding
• What is the ionic formula for sodium chloride?

  Na⁺ and Cl⁻
• What is the ionic formula for lithium oxide?

  Li⁺ and O²⁻
• What do covalent bonds form between?

  Non-metal atoms
• How do covalent bonds form?

  Atoms share electrons to achieve full outer shells
• What is the difference between single and double covalent bonds?

  Single bonds share 1 pair, double share 2 pairs
• What are the properties of giant ionic structures?

  • High melting and boiling points
  • Conduct electricity when dissolved or molten
  • Regular arrangement of oppositely charged ions
• What are the properties of simple molecular structures?

  • Low melting and boiling points
  • Do not conduct electricity
  • Consist of a few atoms held by covalent bonds
• What are the properties of giant covalent structures?

  • Extremely strong due to many covalent bonds
  • Do not conduct electricity (e.g., diamond)
  • Conduct electricity and lubricate (e.g., graphite)
• How many other carbon atoms does each carbon in diamond bond to?

  Four other carbon atoms
• Why does graphite conduct electricity?

  It has delocalised electrons between layers
• What happens to the layers in graphite?

  They can slide over each other easily
• What are two uses of nanoparticles mentioned in the video?

  Sunscreens and detergents
• Why are nanoparticles like titanium dioxide used in sunscreens?

  They block ultraviolet light from reaching the skin
• How do nanoparticles help prevent skin cancer?

  By blocking UV light from reaching the skin
• What is the appearance of titanium dioxide in bulk form?

  It is a white substance
• How does nanoparticulate titanium dioxide differ from its bulk form in sunscreens?

  It is transparent and does not leave white marks
• What is the key reason nanoparticles are used in detergents?

  They are excellent catalysts
• What do catalysts do in chemical reactions?

  They speed up reactions without being used up
• How do nanoparticles in detergents help with cleaning?

  They catalyze the breakdown of dirt faster
• In what other application besides detergents are nanoparticles used?

  Self-cleaning windows
• What are the benefits of using titanium dioxide nanoparticles in sunscreens?

  • Blocks ultraviolet light
  • Prevents skin cancer
  • Transparent, no white marks
• What are the advantages of using nanoparticles in detergents?

  • Excellent catalysts
  • Speed up dirt breakdown
  • Used in self-cleaning windows