1. + Polarity and Intermolecular Forces of Attraction

2. + Covalent bonds mean sharing electrons between atoms…but it isn’t always FAIR/equal. Fluorine LOVES TO GRAB electrons Hydrogen ends up with less electrons

3. + This ability to attract electrons to itself is called ELECTRONEGATIVITY Electronegativity is the ability of an element to attract bonding pair of electrons in a chemical bond.

4. + The periodic table can help us see that going towards Fluorine means increasing electronegativity

5. + periodic table can help us see that going towards Fluorine means

6. + When a bond is POLAR this means we have a partial (+)/electron-poor and a partial (-)/electron-rich area.

7. + Polar Bonds and Lone Pairs contribute to polarity but we need to see if they add or cancel each other. AXE notation?

8. + Polar Bonds and Lone Pairs contribute to polarity but we need to see if they add or cancel each other. AXE notation?

9. + Polar Bonds and Lone Pairs contribute to polarity but we need to see if they add or cancel each other. AXE notation?

10. + Polar Bonds and Lone Pairs contribute to polarity but we need to see if they add or cancel each other.

11. + Exercise: 1. Draw the proper Lewis Structure of a. SOCl 2 b. H 2 S c. HCN 2. Give AXE notation for geometry and identify the shape 3. Show polarities of bonds 4. Determine if the molecule is polar OVERALL or not. Electronegativity Values: S = 2.5 O= 3.5 Cl = 3.0 H= 2.1 C = 2.5 (4.0 = most EN)

12. + Know that we know if our molecules are polar or not, we can know a lot more on how substances behave!

13. + On the basis of attraction of opposite charges, we can list down ways molecules can interact:

14. + Ion-dipole interactions: a permanently charged ion attracts a polar molecule (called a dipole since it has both +/- ends, di- means two, so two-poled)

15. + Ion-dipole interactions

16. + Dipole-dipole, or simply called polar interactions are the next strongest…

17. +

18. + ethanol Sucrose (table sugar)

19. + A special strong version of a dipole-dipole interaction is called HYDROGEN BONDING

20. +

21. + Hydrogen bonding is ESSENTIAL TO LIFE… keeping our proteins, cells, tissues, organs all structured and functioning.

22. + The next interactions, slightly weaker are the ions or dipoles with INDUCED DIPOLES INDUCED DIPOLES – a non-polar molecule that has its electrons slightly affected by polarity of another polar molecule (dipole) It’s like you have a metal object become magnetic too when you put a magnet against it.

23. + The weakest intermolecular force of attraction is called DISPERSION FORCES Think of it as induced-dipole induced- dipole. Molecules have electrons around them, but in blobs that can change. They aren’t orbiting the nucleus in fixed orbits. If the electron cloud/blob changes shape a bit, it becomes slightly polar.

24. + Dispersion forces or non-polar interactions ARE VERY IMPORTANT AS WELL. They can be seen as negative polar-polar interactions.

25. + Dispersion forces, are vital in so many ways…

26. + All these IMFAs (intermolecular forces of attraction) explain so many things around us! SOLUBILITIES…

27. + Why isn’t caffeine very soluble in water?

28. + All these IMFAs (intermolecular forces of attraction) explain so many things around us! MELTING POINTS/ BOILING POINTS Explain why acetone boils/evaporates more easily than water even though it is a heavier/bigger molecule. ACETONE: 56°C WATER: 100°C

29. + All these IMFAs (intermolecular forces of attraction) explain so many things around us! MELTING POINTS/ BOILING POINTS: Both use weak dispersion forces but why do they still differ in boiling points?

30. + All these IMFAs (intermolecular forces of attraction) explain so many things around us! MELTING POINTS/ BOILING POINTS: Both use weak dispersion forces but why do they still differ in boiling points?

31. + All these IMFAs (intermolecular forces of attraction) explain so many things around us! MELTING POINTS/ BOILING POINTS: Both use weak dispersion forces but why do they still differ in boiling points? BOILING POINTS OF HYDROGEN COMPOUNDS OF ELEMENTS PER GROUP (LINE) AND PERIOD (COLUMN)

32. +

33. + Soaps use 2 different IMFA’s: Ion- dipole interactions and NON- POLAR/Dispersion forces ION-LIKE HEAD. With a negative charge RED = Oxygens NON-POLAR TAIL.. Black = Carbon White = hydrogen

34. + The polar/ionic head of soap is called HYDROPHILIC (water- loving) and the nonpolar tail is called HYDROPHOBIC (water- fearing)

35. + Superhydrophobic surfaces use nano-structures on their surfaces to create the lotus- leaf effect.