Chapter 3 (CIC) and Chapter 9 (CTCS) Read in CTCS Chapter pgs Problems in CTCS: 7ab, 9, 13ad, 62bcd

Greenhouse Effect Why does the inside of a car get very hot in the sun (120ºF)? Temp (Calc’d) Temp (Actual) Atmosphere Venus100ºC450ºC96% CO 2 Earth-18ºC15ºC 99% N 2 and O 2 (0.04% CO 2 ) (4% H 2 O)

How do we get data?

Ice Core Data CO 2 was measured in trapped air bubbles Temperature was inferred by deuterium ( 2 H) content. The higher temperature means less 1 H because it weighs less and has a lower b.p.

CO 2 in situ Measurements

Temperature Changes Since the Industrial Revolution

What’s a Greenhouse Gas? Can be almost any gas but N 2, O 2, or Ar (or any monatomic gas) CH 4, CO 2, CFC’s, H 2 O, O 3, SO 2, NO x, CO, etc. How do these differ? We must look at structure VSEPR model predicts simple molecular structure Must do Lewis structure first

VSEPR Valence Shell Electron Pair Repulsion Need to know the number of atoms and lone pairs of electrons around a central atom Multiple bonds are treated just like single bonds In order to be able to do VSEPR, it is required that you be able to draw correct Lewis structures You need to memorize the following table (not the examples)

# areas of e - domains around A Bond -ed atoms Lone pairs Molecular geometry Electronic geometry 2 CO 2 20Linear 3 SO 3 30Trigonal Planar 3 SO 2 21BentTrigonal Planar 4 CH 4 40Tetrahedral 4 NH 3 31Trigonal Pyramid Tetrahedral 4H2O4H2O 22BentTetrahedral Molecule = AX n where A is the central atom

AX 4 Molecules Why are the following molecules the same?

How Does CO 2 Interact with IR Light? UV light can break bonds O 2  2 O Visible light can excite electrons n = 1  n = 2 IR light vibrates molecules Stretches Bends

For these vibrations to absorb IR, the vibration must change the average electrical distribution (A doesn’t do that) N 2, O 2, and monatomics won’t change the average electrical distribution upon vibration B-stretching at 4.26  m C and D- bending at  m

The Carbon Cycle

CO 2 Emission Sources