1. Surface Adhesion and Water Drops Low Surface Adhesion High Surface Adhesion Water molecules attracted to each other (hydrogen bonding) and not to the surface. Forming taller, larger water droplet, will contain more mass. Water molecules attracted to the surface more than to each other. Forming a lower water droplet, will contain less mass.

2. Important Definitions Polymer - substances containing a large number of structural units joined by the same type of linkage. These substances often form into a chain- like structure. polar molecule – molecules that contain a partial positive end and a partial negative end non-polar molecule – molecules that have no partial charges cohesive forces – the forces of attraction between the same type of molecules adhesive forces – the forces of attraction between different types of molecules hydrophilic – attracted to water molecules hydrophobic – not attracted to water molecules surfactant – a substance that is polar on one end and non-polar on the other hydrogen bond- intermolecular attraction of hydrogen atoms that are bonded to a nitrogen, oxygen, or fluorine atom. Wetting – the ability of a liquid to be attracted to the surface of a material

3. Six Recycled Plastics Recycle # and abbreviation NameStructureProperties Polyethylene Terephthalate (PET, PETE) Clarity, strength, toughness, barrier to gas and moisture. High Density Polyethylene (HDPE) Stiffness, strength, toughness, resistance to moisture, permeability to gas. Polyvinyl Chloride (PVC) Versatility, ease of blending, strength, toughness. Low Density Polyethylene (LDPE) Ease of processing, strength, toughness, flexibility, ease of sealing, barrier to moisture. Polypropylene (PP)Strength, toughness, resistance to heat, chemicals, grease and oil, versatile, barrier to moisture. Polystyrene (PS) Versatility, clarity, easily formed