1. DOR: Electron Configuration/Quantum 1) Draw the orbital diagram for Si 2) Which of the following ions has 5 unpaired electrons? a) Ti +4 b) Co +2 c) V +3 d) Fe +3 e) Zn +2 3) Which of the following sets of n, l, m l, m s quantum numbers can be used to describe an electron in a 2p orbital? a) 2, 1, 0, -1/2b) 2, 0, 0, ½ c) 2, 2, 1, ½d) 3, 2, 1, -1/2 e) 3, 1, 0, ½

3. Atomic Mass  Weighted average of element’s natural isotopes  Some isotopes are more abundant than others….  SO atomic mass leans towards more abundant mass

4. How do we calculate atomic mass?  1) Masses of Isotopes  2) Fraction of the abundance of each isotope  usually a percentage  Average atomic mass = mass contributed by all isotopes  Fraction of abundance (isotope mass) = mass from a particular isotope

5. Example 1: Neon has 3 natural isotopes. Ne-20 (90.51%, 19.99244 u) Ne-21 (0.27%, 20.99395 u) Ne-22 (9.22%, 21.99138 u) What is the weighted average atomic mass for Ne?

6. Example 2: Two natural copper isotopes are Cu-63 (62.9298 u) and Cu-65 (64.9278 u) If copper’s atomic mass is given as 63.546 u, what are the percent abundances of these isotopes? Which isotope is the most abundant?

7. Spectroscopy  Analytical method utilizing electromagnetic radiation to determine matter properties  A certain amount of radiation goes through the sample is absorbed SO less intense radiation leaving the sample  I o = I T + I A  Transmittance/% transmittance  T = I T /I o, %T = (I T /I o ) x 100%  Absorbance (A)  A = log (I o /I T ), A = log(100/%T)

8. Mass Spectrometry  Aids in determining the mass of an atom/molecule  Ions or compounds bombarded with electrons, ions fragment and provide unique fragmentation pattern for substance  Ions deflect from their course  Heavy ions---little deflection  Light ions—most deflection

9. Mass Spectrometry (cont.)  Ion separation can occur through the use of a magnetic field  Ion separation via mass/charge ratio  Chart of ion separation generated through spectrometer  Comparison between mass spectrum of one compound to mass spectrum of standard  Enables identification of compound/atom

10. Other Types of Spectroscopy  Infrared Spectroscopy----  Determines structure and analyzes compounds  Ultraviolet Spectroscopy----  Molecule and ion analysis  Nuclear Magnetic Resonance (NMR) Spectroscopy----  Organic molecular structures

11. Homework  Read pp. 42-43, 266-267  Problems p. 67 #33, 39, 40, 41