Topic 2 – Bonding, Structure, and The Properties of Matter

• What is ionic bonding?

  Electrostatic attraction between positive and negative ions
• How strong is the attraction in ionic bonding?

  It is a relatively strong attraction
• How are ionic compounds held together?

  • Held together in a giant lattice
  • Regular structure extending in all directions
  • Electrostatic attraction between positive and negative ions
• What are the properties of ionic substances?

  High melting and boiling points

  
• Why do ionic substances not conduct electricity when solid?

  Because ions are in fixed positions
• When do ionic substances conduct electricity?

  When molten or dissolved in water
• What is important when working out a formula of an ionic compound?

  It must be electrically neutral
• How are ionic compounds formed?

  Through the reaction of a metal with a non-metal
• What happens during electron transfer in ionic bonding?

  Metal gives away outer shell electrons
• What is a covalent bond?

  A shared pair of electrons between two atoms
• Describe the structure and properties of simple molecular covalent substances.

  • Do not conduct electricity (no ions)
  • Composed of small molecules
  • Weak intermolecular forces
  • Low melting and boiling points

  
• How do intermolecular forces change with molecule size?

  They increase with mass/size of the molecule
• What happens to melting/boiling points as intermolecular forces increase?

  Melting/boiling points increase as well
• Describe the properties of diamond.

  • Four strong covalent bonds per carbon atom
  • Very hard
  • Very high melting point
  • Does not conduct electricity
• Describe the properties of graphite.

  • Three covalent bonds per carbon atom
  • Layers of hexagonal rings
  • High melting point
  • Conducts electricity due to delocalised electrons
• Describe the properties of fullerenes.

  • Hollow shaped molecules
  • Based on hexagonal rings, may have 5/7-carbon rings
  • Example: C60 (Buckminsterfullerene)
• Describe the properties of nanotubes.

  • Cylindrical fullerene with high length to diameter ratio
  • High tensile strength
  • Conductivity due to delocalised electrons
• What is metallic bonding?

  Attraction between delocalised electrons and metal ions
• Describe properties of metals.

  • High melting/boiling points
  • Good conductors of heat and electricity
  • Malleable and soft

  
• What are alloys and why are they harder than pure metals?

  • Alloys are mixtures of metals with other elements
  • Different sizes of atoms distort layers, preventing sliding
• What are the limitations of the simple model of atoms?

  No forces between spheres; not true for molecules
• State the uses of nanoparticles.

  • Medicine (drug delivery systems)
  • Electronics
  • Deodorants
  • Sun creams (better skin coverage)
• Why do nanoparticles have different properties than bulk materials?

  High surface area to volume ratio