Gases, Liquids, and Solids: Characteristics and Intermolecular Forces

1. Liquids & Solids Chapter 13

2. Gases • Characteristics: -no definite volume or shape; takes on shape of container -virtually no attractive forces -can be compressed

3. Liquids • Characteristics -definite volume but no definite shape; takes on shape of container -strong attractive forces -need to determine what kind!!! -really can’t be compressed

4. Solids • Characteristics -definite volume -definite shape -strong attractive forces -need to determine what kind!!! -really can’t be compressed

5. Quick Check • Has no definite shape, but has a definite volume = • Has a definite volume and a definite shape = • Gas =

6. Intramolecular vs Intermolecular • Intramolecular - the attraction that results when electrons are given, taken or shared to form a bond.

7. Intramolecular vs Intermolecular • Intermolecular - the attraction of a molecule or particle to another molecule or particle.

8. Intramolecular vs. Intermolecular • Intramolecular forces are always much, MUCH stronger than intermolecular forces

9. Types of Intermolecular Forces • London Dispersion Forces(LDF) - or Van der Waal’s forces. a) attraction between nonpolar molecules-nonpolar molecules. - how do you know if it’s nonpolar? b) Key word is Polarizable - how easy it is to distort a charge.

10. Types of Intermolecular Forces Polarization Nonpolar - even distribution of charge

11. Types of Intermolecular Forces Polarization - + Nonpolar Instant dipole

12. Types of Intermolecular Forces Polarization - + - + Nonpolar Instant dipole Influences others around it

13. Types of Intermolecular Forces London Dispersion Forces 1) Induced or “fake” charge. Molecules will line up + to -. Best stuff to induce a charge?

14. Types of Intermolecular Forces • 1) Big nonpolar molecules (radius)- large electron clouds which induce easier. • A) Hydrocarbons?

15. Types of Intermolecular Forces • 1) Big nonpolar molecules • A) Hydrocarbons? • B) Halogens?

16. Types of Intermolecular Forces • 1) Big nonpolar molecules • A) Hydrocarbons? • B) Halogens? • C) Noble Gases

17. Types of Intermolecular Forces • 2) Slow moving(large mass) - easier to induce charge when moving slow. -> small gases are almost impossible to induce charge

18. Types of Intermolecular Forces Ways to Increase LDF: • Increase the size(radius and mass) • Bigger mass = MORE POLARIZABLE • More polarizable, bigger temporary diopole, holds together better

19. Types of Intermolecular Forces Ways to Increase LDF: • In organic molecules, the longer the chain, the greater the opportunity to induce a charge. Long carbon chains vs isomers?

20. Types of Intermolecular Forces • All molecules have LDF • In nonpolar molecules, LDF is the ONLY force • In other molecules, there are stronger IM forces. Such as…..

21. Types of Intermolecular Forces • 2) Dipole-Dipole Attraction - polar molecules attracted to other polar molecules. • How do you know if it’s polar?

22. Types of Intermolecular Forces • In general, dipole-dipole forces are stronger than LDF. • Why? • In what situation would LDF be stronger than dipole-dipole?

23. Types of Intermolecular Forces • Hydrogen Bonding - not bonding! a) Attraction between Hydrogen and a very electronegative atom(upper right) F, O, N, S

24. Types of Intermolecular Forces • Hydrogen Bonding - not bonding! a) Attraction between Hydrogen and a very electronegative atom(upper right) F, O, N b) Really a special dipole-dipole-> about 10 x stronger special. What does that mean? Increase in attraction!

25. Types of Intermolecular Forces • Hydrogen Bonding - not bonding! c) Big 3: NH3, HF, H20 d) Alcohols show hydrogen bonding- get more attraction e) Dimers - a molecule that has two hydrogen bonds

26. Types of Intermolecular Forces 1b) Ion-Dipole Attraction - attraction of ion and the partial charge of the molecule.

27. Types of Intermolecular Forces 1b) Ion-Dipole Attraction - attraction of ion and the partial charge of the molecule. I) Important in solution making

28. Types of Intermolecular Forces 1b) Ion-Dipole Attraction - attraction of ion and the partial charge of the molecule. i) Important in solution making. ii) Strength becomes greater when charge of ion is greater and/or the size of dipole is stronger.

29. Types of Intermolecular Forces Strength? About 1% of ionic or covalent. Becomes weaker when the distance between molecules increase. Why?

30. Intermolecular Forces • Look at how these forces will effect the following: -> Boiling Points -> Vapor Pressure

32. SOLIDS Types of Solids and their properties

33. Ionic Solids Ionic solids have ions at the points of the lattice. Ex: NaCl

34. Ionic Solids • Characteristics: 1) High Melting Points

35. Ionic Solids • Characteristics: 1) High Melting Points 2) Held together by strong electrostatic forces [Coulomb’s Law] a) the greater the charges of the ions, the greater the electrostatic forces. EX: CaCl2 vs NaCl b) The smaller the ions the greater the attraction. EX: KBr vs. LiF

36. Ionic Solids • Characteristics: 3) Brittle

37. Ionic Solids • Characteristics: 3) Brittle 4) Insulator-won’t conduct in solid state

38. Ionic Solids • Characteristics: 3) Brittle 4) Insulator-won’t conduct in solid state 5) Will conduct in molten state or when dissolved

39. Molecular Solids • Molecular solids have molecules at the points of lattice. EX: Ice, sugar • Held together by dipole-dipole, hydrogen bonding or London dispersion forces-Intermolecular forces

40. Molecular Solids • Characteristics: 1) Stronger intramolecular than intermolecular

41. Molecular Solids • Characteristics: 1) Stronger intramolecular than intermolecular 2) Most only have London dispersion- therfore they need to be big molecules.

42. Molecular Solids • Characteristics: 3) Soft

43. Molecular Solids • Characteristics: 3) Soft 4) Low melting points

44. Molecular Solids • Characteristics: 3) Soft 4) Low melting points 5) Insulator

45. Atomic Solids • Have atoms at the points of their lattice

46. Atomic Solids • Two Types: 1) Metallic Solids - metal atoms at the points of lattice. A) Free moving(nondirectional) “sea” of valence electrons

47. Atomic Solids Metallic Solids - metal atoms at the points of lattice. B) Close packing- arrangement that is most efficient use of space.

48. Atomic Solids Metallic Solids - metal atoms at the points of lattice. B) Close packing- arrangement that is most efficient use of space. 1) Hexagonal close packing - 1st layer in line with 3rd layer

49. Atomic Solids Metallic Solids - metal atoms at the points of lattice. B) Close packing- arrangement that is most efficient use of space. 1) Hexagonal close packing - 1st layer in line with 3rd layer 2) Cubic close packing - 1st layer in line with 4th layer

50. Atomic Solids Metallic Solids - metal atoms at the points of lattice. C) Characteristics: 1. Wide range of melting points.