Material Covered in February
Chemistry 1201
Lecture Section 2
Lecturer: Dr. Elzbieta (Elizabeth) Cook
January
March
April
May
February 28: HOMEWORK #2 was ANNOUNCED (Due on March 7).
You can still pick it up from me or ACCESS IT ON-LINE
It was a HEAVY CLASS - plenty of new and abstract terms:
  • Photoelectric effect
  • Line spectrum of the hydrogen atom (Balmer series observable in the visible part of EMR corresponding to the electronic transitions between n = 3, 4, 5, 6 and n = 2)
  • Matter Waves (qualitatively only)
  • Heisenberg's Uncertainty Principle
  • Quantum Mechanics - Schroedinger Equation and WAVE FUNCTION aka ORBITAL
  • Quantum numbers: n, l , and ml - know the rules for which values thay can adopt and which of their combinations are allowed (permissible)

    • February 26: Chapter 6:
  • New terms: Ground State, Excited state(s), Electromagnetic Radiation (EMR), Wavelength (l) and frequency (n);
  • Know the relationship between l and n and be able to interconvert one into the other (eg. sample ex. 6.1)
  • Quantized Energy and Photons (Planck's Law: E photon = hn)
  • EMR has both WAVE and PARTICLE-LIKE properties (See Photoelectron effect)
  • Line and Band Emission Spectra (Ch. 6.3 - we will cover it quanlitatively only!)
  • The physiscs of the emission spectrum - atom's transitions between states (eg. between an excited state and one of the excited states) are manifested by the emission of light with appropriate wavelength (and frequency). If that wavelength falls into the 400 nm - 750 nm visible portion of the EMR spectrum, one observes colorful spectra.
  • Each atom emits a "fingerprint" emission spectrum (See Fig. 6.14 in BLB)

    • February 19: Titrations = gradual addition of a titrant to an analyte
  • New terms: analyte, titrant, buret, flask
  • calculations for a neutralization titration

    • more stoichiometry - REVIEW
    February 14: Redox reactions - learn how to recognize them
    Reduction (Ox.# goes down, electrons are gained, electrons are used up)
    Oxidation (Ox.# goes up, electrons are lost, electrons are produced)
    New concepts: reducing agent, oxidizing agent
    Concentrations of solutions: MOLARITY - remember to use volume in liters!
    Dilutions - remember that when dilutions are made, the number of moles of solute stays the same.
    ABC of Solution Stoichiometry:
  • Analyze the question (data given, what the question is asking)
  • Balance the reaction equation (use relevant molar ratios, determine the limiting reagent if necessary)
  • Convert units (g to moles and moles to grams; molarities and volumes of solutions to moles, ...)

    • February 7: Quiz on nomenclature.....................................sorry!
    Oxidation numbers - RULES OF FIGURING OUT OX.#'s - know them!
    It really helps to have a good idea what the "elemental forms" of atoms are. For instance, oxygen, in its elemental form occurs as a diatomic molecule, O2 (g); copper is Cu(s), etc. Oxidation number of atoms in their elemental forms is zero (0).
    Redox Reactions: reactions where electrons "change hands" and atoms change oxidation numbers. Such reactions can rarely be balanced by inspection. - RULES OF BALANCING REDOX REACTIONS - know them!
    February 5: ANNOUNCEMENT: HOMEWORK #1 has a mistake in question 5. Please, remove the coefficient of "2" from in-front of H2SiF6.
    Ch.3.5 revisited (from the lecture on Jan. 24). Combustion analysis experiment (~Fig. 3.13) was discussed.
    Recognize that CO2 collected accounts for all carbon in the sample, while all the trapped moisture (H2O) account for all the hydrogen in the sample.
    Consequently:
    nC = nCO2 (because there is ONE mole of C atoms in one mole of CO2)
                                    and
    nH = 2 nH 2O (because there are TWO moles of H atoms in one mole of H2O)
    Ch.4.1-4.2 started. New concepts: strong electrolytes , weak electrolytes and nonelectrolytes ;
    Know what happens to various substances when equeous solutions are made from them.
    Be able to classify solutions of various substances as types of electrolytes.
    Net Ionic Equations: SPLIT strong electrolytes into ions. LEAVE everything as is.
    Eg.: NaOH(aq) + HCl(aq) --> NaCl(aq) + H2O(l)
          Na +(aq) + OH -(aq) + H +(aq) + Cl -(aq) --> Na+(aq) + Cl-(aq) + H2O(l)
    cancel species which appear in the identical form on BOTH sides of the equation:

         Na+(aq)+ OH-(aq) + H+(aq) + Cl-(aq) --> Na+(aq)+ Cl-(aq) + H2O(l)

    Net ionic equation:  OH-(aq) + H+(aq)  --> H2O(l)
    Net ionic equations tell us which species truly participate in chemical reactions (here OH-(aq) and H+(aq)), and which are merely SPECTATOR IONS (here Na+ (aq) + Cl-(aq))
    Be able to write net ionic equations for a variety of types of chemical reactions, eg. precipitation reactions, neutralization reactions, gas formation reactions, etc...