Covalent and Ionic

• What is a simple molecule?

  Just a few atoms joined to eachother by strong covalent bonds
• What are the usual properties of simple molecular substances?

  • Low melting points
  • Low boiling points
• What can simple molecular substances be?

  • Non-metal elements
  • Compounds of non-metals
• What are the attractive forces like of simple molecular substances?

  Weak intermolecular forces
• What happens when a simple molecular substance boils?

  Intermolecular forces are overcome and covalent bonds do not break
• Why do simple molecular substances not conduct electricity?

  Their molecules are not electrically charged and do not contain electrons which are free to move
• What happens to some simple molecular substances when in solution?

  Some of them break down when they dissolve in water, forming ions. These ions can move around, so the solution conducts electricity
• WHy are simple molecular substances insoluble in water?

  The intermolecular forces between water and these substances are weaker than those between water molecules and the molecules of the substance itself
• When do simple molecular substances dissolve in water?

  If they can form strong enough intermolecular forces with the water molecules
• Which simple molecular substances are sparingly soluble?

  Hydrogen and oxygen
• Which simple molecular substances are soluble in water?

  Chlorine, carbon dioxide, sulfur dioxide, sugar and ammonia
• WHich simple molecular substances are soluble?

  Ethanol and ethanoic acid
• What are giant molecular substances?

  Giant molecules consisting of many atoms which are joined by strong covalent bonds and arranged in a regular lattice structure
• What can giant molecular substances be?

  Non mental elements and compounds
• What are the usual properties of giant molecular substances?

  High melting points and high boiling points
• What are giant molecular substances at room temperature?

  solids
• Are giant molecular substances soluble in water?

  No.
• What are two examples of giant molecular substances?

  Diamond and graphite
• What are both diamond and graphite made of?

  Carbon
• What are the properties of graphene?

  A structure that resembles a single layer of graphite where each carbon atom is covalently bonded to three other carbon atoms and it has a regular lattice structure with interlocking hexagonal rings of carbon atoms
• What are properties of graphene?

  • Non-bonding outer electrons become delocalised so it can conduct electricity
  • They can move through the structure
  • Strong
  • Flexible
  • Contains many strong covalent bonds
  • Almost transparent
  • Its layers are just one atom thick
• What are the properties of Buckerminsterfullerene?

  1. Carbon atoms arranged in pentagons as well as hexagons
  2. Conducts electricity because they have delocalised electrons
  3. Are soft when in a solid state because they have weak intermolecular forces
• What are the properties of nanotubes?

  • Closed ends or open ends
  • Conduct electricity because they have delocalised electrons
  • Are very strong because the structure has many strong covalent bonds
• WHat are the properties of diamond?

  Hardness, transparency, high refractive index, high thermal conductivity. Strong covalent bonds between atoms and each atom is bonded to four others
• What are the properties of graphite?

  Each atom is bonded to three others and weak intermolecular forces are between the layers. There are strong covalent bonds between atoms in a layer
• What are metallic bonds?

  Strong electrostatic forces of attraction between positive metal ions and delocalised electrons
• What happens when some metals seem to dissolve in water?

  They react with the water to produce soluble metal hydroxides which dissolve, exposing more metal to the water
• What are the limitations of a drawn structure?

  Does not show:

  • The molecule’s three dimensional shape
  • The bonding and non-bonding electrons