5.2 bonding, structures and the properties of matter

• ionic bonding

  metal + non metal, oppositely charged ions
• ionic compounds 


  giant structure of ions, held together by strong electrostatic forces between oppositely charged ions in all directions
• covalent bonding 


  2 non-metal atoms sharing pairs of electrons
• polymers are large covalently bonded molecules
• giant covalent structures consist of atoms linked together with strong covalent bonds in lattice structure
• small molecules have strong covalent bonds within their molecules, but weak intermolecular forces. these are broken in boiling or melting, not the covalent bonds.
• metallic bonding 


  electrostatic attractions between positive ions and negative delocalised electrons
• delocalised electrons are free to move through metallic bonded structures
• the amount of energy needed to change the state of a substance depends on the strength of the forces between the particles
• the stronger the forces between particles the higher the melting and boiling point of a substance
• limitations of the states of matter model

  there are no forces between particles, particles are represented as spheres, particles shown as solid
• substances that consist of small molecules are usually gases or liquids that have low boiling and melting points
• properties of ionic compounds 


  high melting and boiling points, conduct electricity when molten or dissolved in water (ions are free to move)
• intermolecular forces increase with size of molecules, so larger molecules have higher melting and boiling points
• substances that consist of small molecules don’t conduct electricity because small molecules do not have an overall electric charge
• polymers properties 


  have very large molecules, atoms linked by strong covalent bonds, intermolecular forces are relatively strong
• substances that consist of giant covalent structures are solids with very high melting points
• metals have giant structures of atoms with strong metallic bonding
• metal properties 


  high melting and boiling points, layers able to slide so they can be bent and shaped
• alloys are made from 2 or more different types of metals
• properties of alloys


  different sized atoms distort layers in structure, making it harder for them to slide. harder than pure metals
• metals are good conductors of electricity because delocalised electrons carry charge through metal
• metals are good conductors of thermal energy because energy is transferred by delocalised electrons
• in diamond, each carbon atom is covalently bonded to 4 other carbon atoms.
• properties of diamond 


  very hard, very high melting point, does not conduct electricity
• in graphite, each carbon atom is covalently bonded to 3 other carbon atoms, forming layers of hexagonal rings with weak intermolecular forces
• in graphite, one electron from each carbon atom is delocalised
• properties of graphite


  soft and slippery, can conduct electricity
• graphene 


  single layer of graphite
• properties of graphene 


  conducts electricity, very light but very strong
• uses of graphene 


  electronics and composite materials (solar panels, batteries)
• fullerenes 


  molecules of carbon atoms that have hollow shapes. based on hexagonal rings of carbon atoms, also contain rings with five or seven.
• carbon nanotubes 


  cylindrical fullerenes with very high length to diameter ratios
• cylindrical fullerenes are strong because of strong covalent bonds
• uses of cylindrical fullerenes


  electronics, nanotechnology, strengthening materials
• uses of spherical fullerenes

  catalysts, lubricants, delivering drugs into the body