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Polar

Polar. versus. Nonpolar. By Daniel R. Barnes, init 11/14/2006. SWBAT . . . . . . explain in detail why oil and water don't mix. shared electron pair. covalent bond. =. Formula =. H 2 O. water molecule. electronegativity. 3.5 -2.1. +. +. 1.4. 2.1. unequal sharing of

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Polar

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  1. Polar versus Nonpolar By Daniel R. Barnes, init 11/14/2006

  2. SWBAT . . . . . . explain in detail why oil and water don't mix.

  3. shared electron pair covalent bond = Formula = H2O water molecule

  4. electronegativity 3.5 -2.1 + + 1.4 2.1 unequal sharing of electrons 3.5 - "polar covalent bonds"

  5. + + - - This attraction is an example of an “intermolecular force.” It is a specific kind of attraction called a “hydrogen bond”.

  6. INTERMOLECULAR FORCES HYDROGEN BONDING

  7. nonpolar covalent 2.5 -2.1 2.1 2.5 electronegativity hydrogen carbon 0.4 Formula = octane C8H18

  8. nonpolar covalent 2.5 2.1 + - No +’s No -’s "negligible" DISCLAIMER: C may be slightly negative & H slightly positive, but not enough to matter

  9. nonpolar covalent No +’s No -’s

  10. Huh? + - nonpolar covalent How do gasoline and water interact? No minuses or plusses on the octane molecule, so . . . No attraction, no repulsion. . . . whatever . . . . . . but . . . polar covalent

  11. + + - - . . . so . . . . . . but . . .

  12. Italian Salad Dressing Oily layer Watery layer

  13. What kind of bonds are there in each layer? Example: C--H nonpolar Oily layer Watery layer polar Example: O--H

  14. As a result of polarity differences, how are atoms charged differently? 0 0 0 0 0 0 0 0 nonpolar Oily layer Watery layer polar + - + - + - + -

  15. more CHECKS FOR UNDERSTANDING Q: Why is the bond between H & O polar, whereas the bond between H & C is nonpolar? A: H & C have electronegativities that are almost the same (2.1 & 2.5), whereas H & O have very different electronegativities (2.1 & 3.5).

  16. even more CHECKS FOR UNDERSTANDING Q: Why does Italian salad dressing separate into two layers? A: It contains polar materials and nonpolar materials.

  17. still more CHECKS FOR UNDERSTANDING Q: Why is the oily layer on the top rather than on the bottom? A: Oil is less dense than water.

  18. Water is polar, so when you need to wash, you often need to add soap to the water to dissolve the nonpolar substances like fat, grease, and oil.

  19. H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H ? Sodium Stearate The sodium salt of a fatty acid SOAP “carbon backbone” hydrocarbon  nonpolar covalent bonds Hydrogen and cabon atoms are neutral  Mixes with oily or watery materials?

  20. H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H ? Sodium Stearate The sodium salt of a fatty acid SOAP “carbon backbone” hydrocarbon  nonpolar covalent bonds ? O O Na+ Hydrogen and cabon atoms are neutral ?  Mixes with oily or watery materials?

  21. H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H

  22. nonpolar  oily  “hydrophobic” polar or charged  like water  “hydrophilic”

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