Bonding

• Metallic bonding


  Lattice or grid of ions formed with a cloud of delocalized electrons around them
• Delocalized electrons


  Electrons that are not exactly on the atom, but are free to move
• Metals


  • Make good conductors of electricity and heat
• Ionic bonding


  1. Group 1 metal loses electron

  2. Group 7 atom gains electron

  3. Resulting in a match
• Ionic bonding example


  • Lithium atom donates outer electron to chlorine
• Dot and cross diagram


  Shows where electrons end up in ionic bonding
• In ionic compounds, the charges of all ions must add up to zero
• Ionic compounds


  • Consist of repeating units of ions in a lattice
  • Have high melting and boiling points due to strong electrostatic forces
  • Can conduct electricity only in liquid form or when dissolved
• Molecular ions


  Consist of atoms bonded together, e.g. hydroxide ion
• Any ionic compound can be called a salt, not just sodium chloride
• Covalent bonding


  Non-metals bond by sharing electrons to gain full outer shells
• Structural formula


  Represents covalent bonds with symbols and lines
• Covalent bonding


  • Number of bonds an atom makes is the same as the number of electrons it needs to gain a full outer shell
• Simple molecular/covalent structures


  • Have relatively low boiling points due to weak intermolecular forces
  • Cannot conduct electricity even as liquids
• Giant covalent structures


  • Atoms form covalent bonds to other atoms, forming one giant molecule
  • Examples: diamond, graphite
• Allotropes


  Different structures of the same element, e.g. diamond and graphite
• Graphite


  • Consists of layers of carbons with delocalized electrons between layers, allowing it to conduct electricity and slide easily
• Metal alloys


  Mixtures of metals that are stronger than pure metals due to disruption of the regular lattice
• Nanoparticles


  Structures between 100-2500 nanometers in size
• Surface to volume ratio

  Ratio of a particle's surface area to its volume, which is higher for smaller nanoparticles