Properties of materials

• How many covalent bonds can carbon form?

  Four
• Why is there a vast array of natural and synthetic organic compounds?

  Due to carbon's ability to form families of similar compounds, chains, and rings
• What are the properties of diamond?

  • Very hard
  • High melting point
  • Does not conduct electricity
  • Each carbon is joined to 4 other carbons covalently
• How many carbons is each carbon joined to in graphite?

  Three
• What are the properties of graphite?

  • Soft and slippery
  • Can conduct electricity
  • Layers of hexagonal rings with no covalent bonds between the layers
  • One electron from each carbon atom is delocalised
• What is the shape of Buckminsterfullerene?

  Spherical
• What are fullerenes?

  • Molecules of carbon atoms with hollow shapes
  • Based on hexagonal rings of carbon atoms
  • May also contain rings with five or seven carbon atoms
• What is graphene?

  Single layer of graphite
• What are the properties of graphene?

  • Useful in electronics and composites
  • Has properties that make it useful in these applications
• Why do changes of state occur at different temperatures?

  Due to energy transfers and the relative strength of chemical bonds and intermolecular forces
• What happens when energy is transferred to a compound?

  Melting or boiling occurs
• What happens when energy is transferred from a compound?

  Condensing or freezing occurs
• What are the relative strengths of covalent and ionic bonds?

  • Covalent bonds are very strong
  • Ionic bonds are very strong due to electrostatic forces of attraction
• Why do simple molecules melt and boil easily?

  Because the weak intermolecular forces are overcome, not the covalent bonds
• Why do ionic compounds have higher melting and boiling points?

  Because the electrostatic forces of attraction are harder to overcome
• What are the factors that result in different temperatures at which substances change state?

  • Energy transfers
  • Relative strength of chemical bonds
  • Intermolecular forces
• How can you predict the state of a substance under given conditions?

  By using data to determine if the temperature is below the melting point, between the melting and boiling point, or above the boiling point
• How do the bulk properties of materials relate to the types of bonds they contain and their bond strengths?

  • Ionic compounds have high melting and boiling points due to strong electrostatic forces
  • Simple molecules have low melting and boiling points due to weak intermolecular forces
  • Giant covalent structures have high melting and boiling points due to strong covalent bonds
  • Polymers and metals have varying properties depending on their bond strengths and arrangements
• What is the surface area to volume ratio of nanoparticles?

  Very large
• What are the properties of nanoparticles?

  • High surface area to volume ratio
  • Contain a few hundred atoms
  • Are smaller than fine particles (PM2.5)
• What is the size range of nanoparticles?

  1-100 nanometers
• How does the surface area to volume ratio affect the properties of materials?

  As the side of a cube decreases, the surface area to volume ratio increases, making the material more reactive
• What are the uses of nanoparticulate materials?

  • High surface area to volume ratio makes them good catalysts
  • Can be used to produce highly selective sensors
  • Nanotubes could make stronger, lighter building materials
  • Can be used in cosmetics, lubricant coatings, and small electrical circuits
• What are the possible risks associated with nanoparticulate materials?

  Unknown, as they are still being created and tested, and may interact with cells in unknown ways