1. The Future (?) Data from past 100 years: CO 2 conc. has risen by 25% average temp. increase: 0.5-0.7 0 C Current: doubling the CO 2 conc.  +1.8-6.3 0 C (2.5-10.4 0 F by 2100) CO 2 is a major part of the greenhouse effect Earth’s average temperature is increasing

2. Shape of Molecules (3.3) Greenhouse gases: CO 2, CH 4, N 2 O, O 3, H 2 O, CFCs Not greenhouse gases: O 2, N 2, Ar Why the difference? Shape!

3. VSEPR Lewis structures: 2D Reality: 3D Bonds are made of electrons  Negatively charged  Repel each other (still attracted to protons)  Want to be as far apart as possible!

4. Example: Methane CH 4 : tetrahedral C H H H H 109. 5 H H H H C

5. Fig.3.7

6. Fig.3.8

7. Fig.3.9 “Trigonal Pyrimidal”

8. Fig.3.10 “Bent”

9. Fig.3.11 “Linear”

10. Fig.03.12 “Bent”

11. Light and Molecules (3.4) UVB, UVC: Bonds break IR: Can’t break (not enough energy) Can cause vibrations Shape  HOW a molecule can vibrate Which wavelength? Bond strength & flexibility, atom masses

12. Fig.03.13

13. Fig.3.14

14. What about O 2 and N 2 ?  Do not absorb IR radiation  IR does not cause vibration  Can’t “trap” heat  Not greenhouse gases

15. Fig.3.16

16. The Carbon Cycle Sect. 3.5

17. Fig. 3.17 Where does CO 2 come from? Where does it go?

18. Sources of CO 2 CaCO 3 (limestone) water Plants & animals Respiration/decay Volcanic vents CO 2 (natural)

19. Consumption of CO 2 CO 2 Plants Respiration water H 2 CO 3 Pressure/time Fossil Fuels Mineral Dep.

20. Fossil Fuel Contribution to Atmospheric CO 2 : 6-7 billion tons of carbon released ~ ½ goes to atmosphere Since 1860: – CO 2 conc. 290 ppm  375 ppm, – Increases ~1.5 ppm/year.

21. Deforestation Adds CO 2 to air (burning/decay) Takes away a CO 2 remover (trees/plants)

22. Excess CO 2  global warming Increase in atmos. CO 2 is a concern – 3.1-3.5 Gt of carbon/year How much CO 2 is added per year?

23. Quantitative Concepts: Mass (3.6) How much does an atom weigh? Depends on the atom Standard: Carbon-12 Mass # Atomic #: 6 6p, 6n One Carbon 12 = 12 amu

24. C 6 Carbon 12.01 Atomic # Symbol Name Atomic Mass

25. Carbon: 3 isotopes Carbon-12: 98.89% Carbon-13: 1.11% Carbon-14: ~0.00% Average atomic mass for C = 12.01 amu What’s with the 12.01??? Atomic mass is an average of all carbon atoms

26. NO carbon atoms weigh 12.01 amu Treat ALL carbon atoms as though they weigh 12.01 1 Tbs of carbon has about 6.022 x 10 23 carbon atoms – 602,200,000,000,000,000,000,000 Dealing with large numbers of atoms – Average is best