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Notes to teachers This slide should NOT be displayed

Notes to teachers This slide should NOT be displayed. The purpose of this presentation is to… Introduce the basic science behind the “Goo” experiment / investigation.

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  1. Notes to teachersThis slide should NOT be displayed The purpose of this presentation is to… Introduce the basic science behind the “Goo” experiment / investigation. There is an opportunity to emphasise that there are a number of representations used to explain what happens in nature. These are NOT actually what happens, but that they are “Models” to help us visualise a specific set of circumstances. The presentation is NOT intended to teach topics for the first time, but to revise some aspects of chemistry (monomer / polymer / covalent bonding) and to give an insight into an aspect of chemistry at A’ level (polarity, H bonding). Taken with the experiment, there is an opportunity here to highlight the fact that chemistry and physics can be linked together to modify the mechanical properties of a polymer by using a reaction to cross link polymer chains and design a polymer with a specific viscosity. An investigation of viscosity v cross links could follow. This using science for practical (and commercial) use is Materials Science.

  2. Goo – How it works(Without getting too stuck on details)Martin Carr(Oxford University Department of Materials)email: Martin.Carr@materials.ox.ac.ukweb: http://outreach.materials.ox.ac.uk

  3. Easy Words Goo is made from a polymer called… Poly Vinyl Alcohol …which is the main part of PVA glue Poly = Lots of identical bits Vinyl = Name for repeat units of C-C Alcohol = A special, covalent –OH group

  4. Easy Molecules C C C C OH C C O O OH C C This is how we represent ordinary alcohol… C2H5OH This is how we represent Vinyl alcohol… C2H3OH

  5. Easy Polymer OH C C n Hundreds of thousands of Vinyl Alcohol monomer molecules (mer means molecule) join together in a chemical reaction to make a Polymer. The molecule is too big to draw every single atom, so we have a shorthand where “n” is the number of joined monomer molecules…

  6. Medium – Bonding Slightly -ve Slightly -ve Slightly +ve O H Representing a Polar molecule • Polymers are made using covalent bonds to join atoms. • Electrons are shared between atoms. • The Alcohol, -OH, also uses covalent bonds. • The electrons are NOT always equally shared O H

  7. Harder – Hydrogen Bonding H H H H H H O O O O O O Electrostatic Attraction (Hydrogen Bond) C C C C C C C C C C C C Long Molecules with lots of Polar, -OH, Groups …are next to similar molecules… The groups attract and make it harder to slide past each other.

  8. The Finale H H H H H H H H H O O O O O O O O O C C C C C C C C C C C C C C C C C C The Borax 2- anion Attracts more strongly And holds more Chains together Borax -- ion

  9. Thank You For Listening. Now it’s your turn…

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