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Water notes only
- 1. Water as amolecule
- 2. Water as amolecule • Water has a polar covalent bond • The electrons are shared unevenly • Oxygen is stronger, so it pulls the electrons to itself
- 3. Water as amolecule • Water is a polar molecule • One part is more negative, and one part is more positive
- 4. Water as amolecule • The polar parts of water will connect, giving water special properties **You will see these properties in lab**
- 5. Vocabulary • POLAR –a molecule that has an uneven distribution of electrons • POLAR - una molécula que tiene una distribución desigual de los electrones • POLAR - 的分子，具有電子的不均勻分佈
- 6. Vocabulary • Cohesion –when similar things stick to each other (ex: water molecule to other water molecules to form drops) • Adhesion – When different things stick to each other (ex: water sticks to grass)
- 7. Lab part 1 •Talk in lab group – record in notebook – What did you observe? – Explain why you saw what you did • Share out – whole group – Many drops could fit on the penny than we predicted – This happened because of cohesion. The water molecules stuck to each other to allow more water to fit.
- 8. Lab part 2 •Talk in lab group – record in notebook – What did you observe? – Explain why you saw what you did • Share out – whole group – The paper clip could float on water. – This happened because of cohesion. The water molecules stuck to each other to allow more water to fit.
- 9. Lab part 3 •Question: How do different chemicals affect the surface tension of water? • Safety!! – Wear goggles when handling chemicals • Make sure to get your procedure approved BEFORE conducting your experiment • Use a new pipette for each solution to avoid contamination (mixing the chemicals by accident)
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- 11. Vocabulary • Nonpolar -a compound where electrons are shared equally. Areas of the compound are neutral. • Hydrophobic – “scared of water” a substance that does not dissolve in water. Nonpolar substances are hydrophobic. • Hydrophilic – “Water loving” a substance that will dissolve in water. All polar substances are hydrophilic
- 12. Detergents (Soap) • Micelle – Forms when hydrophobic ends clump together • Detergent molecules have a polar end and a non polar end
- 13. Detergents • Amphiphilic –has a polar and a nonpolar end. Detergents have a hydrophobic end and a hydrophilic end. The polar end will dissolve in water The nonpolar end will dissolve in oil
- 14. Properties of water •Cohesion – water sticks together • Resistance to temperature change – needs a lot of energy to raise temperature • Density – solid ice floats in liquid water • Universal Solvent – can dissolve almost anything
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- 17. How soap dissolvesoil • Green head=hydrophillic, polar, dissolves in water • Yellow tail – hydrophobic, nonpolar, dissolves oil • LIKE DISSOLVES LIKE
- 18. Quiz next week:Properties of water • 4 properties from reading # 3.5 • Solubility • Polar • Non-polar • Amphipathic • Experimental design – Controlling an experiment
- 19. As you read… Createdefinitions for the following terms • Solubility • Solute • Solvent • Homogeneous • Solution • Mixture
- 20. Vocab • Mixture -a system where 2 or more things are combined, but not chemically • Solution – when 2 or more things are combined evenly • Solubility – The amount of solute that can be dissolved by a solvent
- 21. Vocab • Homogeneous mixture – a mixture that is evenly mixed. (ex. CO2 bubbles in soda) AKA a solution • Heterogeneous mixture – a mixture that is unevenly mixed. (ex. Sand in water)
- 22. Vocab • Solvent –the substance that dissolves the solute (often, it is water) • Solute - the substance that is dissolved