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
Atomic Mass Weighted average of element’s natural isotopes Some isotopes are more abundant than others…. SO atomic mass leans towards more abundant mass
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
Example 1: Neon has 3 natural isotopes. Ne-20 (90.51%, u) Ne-21 (0.27%, u) Ne-22 (9.22%, u) What is the weighted average atomic mass for Ne?
Example 2: Two natural copper isotopes are Cu-63 ( u) and Cu-65 ( u) If copper’s atomic mass is given as u, what are the percent abundances of these isotopes? Which isotope is the most abundant?
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)
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
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
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
Homework Read pp , Problems p. 67 #33, 39, 40, 41