Memorandum

To:       CHM 1045 Recitation Instructors
          Dillhyon, Martin, Callihan, Guile

From:     Robley Light

Date:     February 26, 1996

Re:       Recitation 8, week of February 26


     Hand back quizzes and go over them.

     I handed back group problem 2.  I'm sending you a copy of a
solution on email, in case you get questions about it.  I graded
these myself, but if anyone has questions on the grading, send them
to me.  (Assigned grades were somewhat subjective).

     For new material, go over a calculation of energy, wavelength,
and frequency of a photon emitted or absorbed when the hydrogen
atom drops (light emitted) or jumps (light absorbed) from one Bohr
orbit to another.  The Rydberg constant would be given in a
problem.

     Review orbital names and characteristics, including quantum
numbers associated with each and the number of nodes in an orbital
(nodes=n-1, if one ignores infinity as a node;  angular nodes=l)

     Review electron configuration of atoms and ions, giving both
long form and truncated form (i.e. [Ar]4s2 for Ca.).  Transition
metals lose electrons from the s orbital first when they ionize
even though it is the d electrons that have been "added" last. 
Tell them not to worry about the "exceptions" such as Cr being
4s3d5 rather than 4s23d4, but they should have some feeling for why
this happens.  They should be able to identify an element from its
electron configuration, and should be able to use the periodic
chart to write electron configurations.

     In periodic trends chapter, concentrate on sizes of atoms, and
ionization energies, both which have definite trends in relation to
the table, and relative size of an atom and its ion.  Mention
electron affinity, but these trends are more complicated and we
won't dwell on them.