Bonding, Structure and the Properties of Matter

• Solids


  Have a very thick structure, atoms may wiggle a little bit but are in fixed positions, cannot flow or be compressed
• Liquids


  Have more movement than solids, can flow but cannot be compressed
• Gases


  Have a lot of movement, not in fixed positions, can flow and can be compressed
• A compound has a melting point of 19 degrees and a boiling point of 74 degrees
• At room temperature (25-27 degrees), the compound will be in the liquid state
• Boiling point = condensing point, melting point = freezing point
• State symbols


  S = solid, L = liquid, G = gas, Aq = aqueous
• If a liquid and solid or liquid and gas are combined, you may see bubbles or a loss of mass
• Ionic bonding


  Transfer of electrons from a metal to a non-metal
• Ionic charges


  • Group 1 = +1, Group 2 = +2, Group 6 = -2, Group 7 = -1
• Forming ionic compounds


  1. Non-metal keeps its electrons, metal transfers electrons to non-metal

  2. Draw dot-cross diagrams and indicate charges
• Covalent bonding


  Sharing of electrons between two non-metals
• Metals


  • Positive ions in a sea of delocalized electrons, allows conduction of electricity and heat
• Alloys


  • Contain positive metal ions and delocalized electrons, plus another element
• Pure metals


  • Have layers that can slide over each other, making them soft
• Alloys


  • Have distorted layers that cannot slide, making them hard
• Ionic compounds


  Have a giant ionic lattice structure
• Properties of ionic compounds

  • High melting/boiling points, only conduct when molten or dissolved
• Simple covalent compounds


  Have small molecular structures
• Properties of simple covalent compounds

  • Low melting/boiling points, generally gases or liquids at room temp, do not conduct electricity
• Giant covalent compounds


  Made of carbon, have a giant covalent structure
• Giant covalent compounds


  • Diamond, graphite, fullerenes
• Diamond


  • Incredibly hard, each carbon makes 4 bonds
• Graphite


  • Soft, each carbon makes 3 bonds, conducts electricity
• Fullerenes


  • Made of carbon, incredibly hard but can be used as lubricants, potential uses in reinforcement and drug delivery
• Polymers


  Molecules made of many repeating units, properties depend on presence of cross-links
• Nanotechnology


  Manipulating atoms and molecules at the nanoscale, can give materials very different properties
• Nanotechnology has huge potential in areas like communications and medicine, but also raises concerns