Intermolecular forces for college chemistry course

Intermolecular forces for college freshman chemistry course

1. INTERMOLECULAR FORCES 1

2. Intra molecular forces Inter molecular forces Forces between the atoms within a single molecule Forces between two or more molecules (similar/dissimilar) Stronger as they involve the actual sharing of e - Weaker as they deal only with interactions of e - 2 https://opentextbc.ca/chemistry/chapter/10-1-intermolecular-forces/

3. Significance State of matter 3 https://opentextbc.ca/chemistry/chapter/10-1-intermolecular-forces/

4. Significance Melting point and boiling point 4 http://eschooltoday.com/science/states-and-behaviour-of-matter/changing-states-of-matter.html

5. Significance Viscosity 5

6. 6 van der Waals forces

7. Ionic forces 7 Attractive Very strong NaCl has a melting point of 801 °C

8. London dispersion forces Momentary nonsymmetrical electron distribution Increases with molar mass Operate in any substance Weak 8

9. Halogen Molar Mass Melting Point Boiling Point Fluorine F 2 38 g/mol 53 K 85 K Chlorine Cl 2 71 g/mol 172 K 238 K Bromine Br 2 160 g/mol 266 K 332 K Iodine I 2 254 g/mol 387 K 457 K Astatine At 2 420 g/ mol 575 K 610 K 9 Melting and Boiling Points of the Halogens

10. Dipole-dipole 10 Electronegativity

11. Dipole 11

12. Dipole-dipole 12 Between polar molecules Weak

13. Hydrogen bonding H bound to small electro- ve atoms like O , N and F Strong 13

14. 14 Hydrogen bonding Dipole-dipole

15. Question time Example 1 Which will have the higher boiling point: N 2  or CO? Explain your reasoning. Example 2 Which of these has a greater extent of intermolecular forces: ICl or Br 2 ? Why? Example 3 Ethanol C 2 H 5 OH and methyl ether CH 3 OCH 3  have the same molar mass. Which has a higher boiling point and why ? 15

16. Ion-dipole 16 Ions and polar molecules Strong

17. Induced dipoles Dipole-induced dipole Ion-induced dipole 17

18. Strength of forces Ionic Ion-dipole Hydrogen bonding Dipole-dipole London dispersion 18

19. 19 Liquid Gas WHY?

20. DNA 20

21. 21 Geckos could stick to: Silicon dioxide (polar) G allium arsenide (non-polar) https://robotics.eecs.berkeley.edu/~ronf/Gecko/

22. Homework CaCl 2 H 2 NO H 2 O Ar 1. CaCl 2 > H 2 > NO > H 2 O > Ar 2. NO > H 2 O > CaCl 2 > H 2 > Ar 3. H 2 O > H 2 > NO > CaCl 2 > Ar 4. H 2 O > CaCl 2 > NO > Ar > H 2 5. CaCl 2 > H 2 O > NO > Ar > H 2 22 List the substances in order of decreasing (highest to lowest) boiling point: