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Fall-09
C H E M * 2 0 6 0     S t r u c t u r e  a n d  B o n d i n g     F a l l - 2 0 1 0
     
8 Dec 2010

Question:
I was wondering if we were required to know how to draw the compounds with particular crystal structures (such as antifluorite, cesium chloride, fluorite, nickel arsenide, peroivskite and rock salt) as per pages 17 and 18 in part 5b, or if we were just required to recognize them, or if they were just supplementary to the lecture's topic.
Answer:
You have to be able to recognize the six types (note that drawings may vary).
You have to understand and be able to draw schematically the cubic types (NaCl, CsCl, fluorite and sphalerite).


3 Dec 2010

Question:
The metallic radii is half the distance between two neighbouring metals in a crystalline solid and the van der Waals (vdW) radii is half the distance between two approaching atoms when the vdW interaction is minimal. To me these sound very similar or in fact the same, are they? The stated radii in the tables available to us have different values for each interaction. I convinced myself that the reasons behind this are because of the definitions of the radii. Metallic radii are experimentally determined from a solid state (lower energy), whereas vdW can be measured using all kinds of techniques in different phases (solution-nmr can measure vdW contacts of protein ligand interaction). Am I totally off base here?
Answer:
I would say you are right although there is some ambiguity in your wording.
If we have metal element in a crystalline state, then half the distance between the contacting atoms is their metallic radius.
It is not so straightforward to determine the van der Waals radius of a metal but yes, it corresponds to a minimum on the potential curve when two atoms approach each other without making a chemical bond.
In practice it is assumed that van der Waals radius of an atom does not change when it is part of a molecule (unless there is  significant charge on this atom in the molecule). Therefore, we can see the distance between contacting atoms while they are parts of two neighboring molecules and determine their van der Waals radius as half the distance.

 
29 Nov 2010

Quiz 3 results: average grade (88 students) is 9.12 out of 12. In general, the results are very good. Math seems to be a problem for some students.

 
17 Nov 2010

A pdf copy of Quiz 3 will be posted on the website by Friday. Those who did not attend the lecture today will be able to print a copy of quiz and use it as a valid examination copy. The deadline for the return of completed forms is the same: the noon of Mon, 22 Nov 2010

 

 
17 Nov 2010

Question:
The question says to estimate the thickness of the surfactants, does this mean we're allowed to make assumptions about the molecule. For example treating the terminal methyl group as a sphere with a radius of 2.0 angstrom or treating an O or N along the hydrocarbon chain as C atom. These assumption were used in the problem sets, but since this is a take-home quiz I want to know if you'll require a more precise answer.
Answer:
You can use these assumptions and do your calcs to the same level of accuracy as in the problem set tasks. Note that the question #1 says "Estimate ..." as opposed to "Calculate ..." in questions ## 2,4 and 6. However, still your answer has to be accurate within 1 Angstrom.

 

 
17 Nov 2010

Quiz 3 take-home examination started at noon. Completed examination forms must be returned by the noon of Mon, 22 Nov 2010

 
24 Oct 2010

Midterm exam-2009 and solutions have been posted. Note that in 2009 the exam covered slightly different material and you have to skip some of the questions. Also, in 2009 the students were not allowed to use a formula sheet and therefore the structure of questions was different.

 
12 Oct 2010

After Quiz 1/2 some students asked why 1,3-dichloroallene is chiral even though it does not have any tetrahedral carbon chiral centers (Task #5 in In-class Part). This is true, none of the carbon atoms in the molecule is a chiral center but the molecule is chiral as a whole (so-called axial chirality). In our course we used a more general criterion to determine if a molecule is chiral: the absence of an improper rotation axis. This is the case: the molecule lacks such an axis and therefore it is chiral. Look at the very last page in the answers to see two optical isomers of the molecule.

 
12 Oct 2010

Quiz 1/2 answers have been posted on the website and therefore the mark for the Take-home Part of the quiz becomes zero if this part of the quiz has not been returned. Three students have not returned the Take-home part.

 
27 Sep 2010

Question:
Question 8 of problem set 2 requires to fill in information on group #120, however in order to access the group information on the website a user name and password is required.
Answer:
Our university has a subscription for this resource.
That means you can freely access the site using any university computer (e.g. in the library) or using your own laptop when you are on the campus and use wireless connection.
If you are trying to access the webside from another location, you may not be able to use the resource.


27 Sep 2010

Lecture room change:
    Starting Wed, 29 Sep 2010 the lecture room has been changed from MCLN-102 to MACS-209.
    Several students complained and I agree that this change infringes upon students' rights. There is not much that I can do as the Registrarial Services did not ask, but rather notified me. They say there are bigger classes that had to be moved:
"In order to accommodate two larger classes, CHEM 2060 must be relocated for the remainder of the Fall 2010 semester. I regret any inconvenience to the instructor and class, but issues with the two larger classes being overloaded force changes at this point in order to properly seat students and conform to fire codes." (Message from Registrarial Services)
    If you want to express your concerns, I encourage you to e-mail to the Chair of the Chemistry Department Prof Adrian Schwan: schwan@uoguelph.ca


20 Sep 2010

Problem Sets and Solutions: Problem sets comprise tasks for homework and tutorials. Solutions of selected tasks will be given during tutorials and/or posted on the website (typically after the corresponding tutorial).