Monday, November 29, 2010

Corrections and Extensions

First, it was brought to my attention that I had a couple of wrong answers on the Organic Chemistry Practice Test. I named the number of carbons wrong in numbers 16 and 17. I counted seven, but used the base name Hex- instead of Hept- like I should have. I have made corrections and have posted the corrected version of the key on the Events Calendar.

Also, I am going to extend the due date of the Organic Chemistry independent study until next Monday, December 6th. I really want as many people to complete the independent study as possible. It is a minor part of the AP Chemistry exam, but any little bit will help to get a passing score for you. I will also extend the Jmol extra credit until next Monday.

I have posted the Chapter 10 homework on WebAssign. Please keep up on the assignments. Make it a goal to do five problems a night starting tomorrow night. This will make the homework not such a burden to you right before the exam. Also, you will be practicing while I am lecturing on the material. Please make sure to view the VODCasts posted on the dates Nov. 29th and 30th, and Dec. 1st and 2nd. Like I said in class today, I will lecture the material, but it will be at lightning speed. I want to use the class time for demonstrations and concept discussions. The VODCasts give examples of most of the problems that you will see on WebAssign. Anything not covered by the VODCasts, I will lecture on in class.

The final test/exam of the semester will be the Tuesday before final exams start. The test will cover all of Chapter 10 and most / if not all of Chapter 11. We should be done with Chapter 10 by this upcoming Friday. We will spend next week on Chapter 11. What material from Chapter 11 that can be covered from Monday to Friday of next week will be on the exam. You will have access to a review for the test beginning late next week and a key will be supplied. Monday, December 13th will be used as a review for the test on Tuesday.

On finals day, we will go over the final test of the semester. We will complete a lab on that day. The lab will deal with the concept of chromotography. I will ask that you complete the lab write-up that night (Thursday, December 16th) and turn the lab in to me the next day before you leave on winter break.

Thursday, November 25, 2010

EXTRA CREDIT! EXTRA CREDIT!

As promised, a true extra credit opportunity. This will be worth 15 points towards your homework grade. Your mission, if you choose to accept it, will be to download a virtual molecule building program from the internet and use the program to build a virtual molecule. If you try to build the molecule that I designate for you and email the file to me, you will get 10 of the possible 15 points. To get the remaining 5 of the 15 points, the molecule must be built correctly. If you Google the molecule that I designate for you, you should be able to find an image and just replicate that image. My goal for this project is not for you to build the molecule correctly (though I would like that to happen), but rather that you familiarize yourself with the software.

The software is called Jmol, and it is freeware. Use the link to go to the site and follow the directions on how to download the software. You may need a decompression program to extract the files from a folder. I have made a short PODCast how to download the program and use it. It is labeled Jmol Demo and can be found on the date November 25th on the Events Calendar. Please email the completed file to me at cbrueckner@lps.k12.co.us.

Below are the designations for what organic compound you are to build.
  • If your last name starts with "A" through "G" - build the compound cis-difluoroethene.
  • If your last name starts with "H" through "L" - build the compound 2-Butene.
  • If your last name starts with "M" through "P" - build the compound Propyne.
  • If your last name starts with "S" - build the compound Butanol. **If your last name starts with "Si" and you have a XY chromosome, you must build Isobutanol. But if your last name starts with "Si" and have a XX chromosome, you will still build Butanol. If the "Si's" of the class do not understand what I mean, you better look up chromosomes.
  • If your last name starts with "T" through "Z" - build the compound trans-difluoroethene.
To all in the class. If anyone can build Methylbenzene and send me the file, it will be worth another 5 points extra credit towards your homework grade. Good luck and look back at the blog this weekend for some other information that I will be putting out about the chapters in the book that will be covered after the Thanksgiving break.

Wednesday, November 24, 2010

Organic Chemistry Test Posted

I finished the Organic Chemistry Test and it has been posted on the Events Calendar under the date Wednesday, November 24th. The test will be worth a total of 29 points that will go towards your ASSESSMENT (60% OF YOUR GRADE) category. This is a great opportunity for everyone to have a really good test score to help your overall grade.

When answering the written questions: (1) make sure to define any terms that you may use; (2) when comparing molecules, make sure to highlight similarities and differences between the molecules; and (3) reference any figures that you may draw to represent the compound(s) in question.

The test is a little different than the practice test. In the test, I have taken some liberties to incorporate concepts from past units into organic chemistry. One is polarity of molecules. A polar molecule is asymmetrical in relation to dipoles within the molecule. A non-polar molecule is symmetrical in relation to dipoles within the molecule. I have also incorporated chemical reactions, like the AP Chemistry test will do. Remember, most organic compounds are hydrocarbons. You need to know what is produced when a hydrocarbon combusts.

Good luck and email me if you have any questions.

p.s. Look tomorrow at the blog for a true extra credit opportunity.

Solutions Movie Available and a Change

I just wanted to let everyone know that the solutions are available on the Events Calendar under the date November 23rd. Sorry that I did not get it on the calendar yesterday, but the movie took a lot longer to make than I expected. I hope to have the actual test for the organics independent study posted later today. If not, it will be very early on Thursday morning, November 25th. You can watch the Macy's parade and some football while you do your test. :) Please email me if you have any questions.

There are two changes to the practice test that I made. If you downloaded the practice test prior to 2:00 pm yesterday, you will have to make changes to two problems, #30 and #31.
  • #30 was changed from 5-Bromo-1-Pentene to 5-Bromo-1-Pentyne
  • #31 was changed from cis-3-Hexyne to cis-3-Hexene
If you downloaded the file yesterday late in the afternoon or last night, the correction was already made on the practice test. The file on the calendar now has the change in it.

Monday, November 22, 2010

HELP FOR YOUR GRADE! (If you want it.)

I hope that everyone is having a good break so far. As I promised in class on Friday, November 19th, I have a couple of ways to help you improve your grade. Not all of the ways are extra credit like I wrote on the board, but it is even better! (For your grade that is, not you.)

First, I am going to offer an opportunity for you to complete a independent study unit on Organic Chemistry, which is Chapter 25 in your book. This will be a short, but complete unit on the chemistry of carbon. AP Chemistry is a course designed to be equivalent to an upper level college freshman chemistry course. Therefore, after the successful completion of freshman chemistry, a chemistry, biology, pre-med, or chemical engineering major would move on to a year long course in organic chemistry. The branch of organic chemistry in the chemistry tree is the largest. It is the chemistry that is the back-bone of the pharmaceutical industry, petroleum industry, and almost everything you buy without a prescription at the corner drugstore. Thousands of new chemicals are discovered every year and the vast majority of them are organic compounds. It is incredibly important, so a very minor amount of information known about it will be a benefit to you. This would help as you possibly move on to AP Biology, or get a 4 or 5 on the AP Chemistry exam and move right into organic chemistry in your first year of college, or most important for right now, see a couple of questions pertaining to organic chemistry on the AP Chemistry exam. I do not cover this material in class because it historically is a very minor part of the exam and there just is not enough time to cover everything during the course, but also enough of the exam that it could be the difference for some to passing the exam or moving to the 4 and 5 region of the exam.

THIS INDEPENDENT STUDY UNIT IS OPTIONAL AND NOT REQUIRED FOR THE COURSE. IT IS DESIGNED TO BE AN ENRICHMENT TO THE COURSE AND A VERY MINOR PORTION OF THE AP CHEMISTRY EXAM.

The unit will consist of you reading the chapter and studying the Chapter 25 Power Point that is available on the class Events Calendar, completing a practice test, and then finally completing a written take home quiz that will turned into me at the beginning of class Monday, November 29th, 2010. This take home quiz will be 20 questions. This is an opportunity for you to add a really good score to your assessment grade. It will be open book, open note, open internet, and open study buddy if you choose. I would suggest that everyone who wants to improve his or her grade take this opportunity and also those that are really serious about scoring well on the AP Chemistry test. The test is the only part of this independent unit of study that will be graded.

  • The Chapter 25 Power Point can be found on the Events Calendar of my AP Chemistry web-page under the date of Sunday, November 21st, 2010. I have eliminated about 1/3 of the chapter from the Power Point. The independent study will focus on the classifying and naming of organic compounds and certain functional groups. Also, molecular geometry, bond angles, and hybridization that was learned in the previous unit will be applied to organic molecules.
  • The Chapter 25 practice exam will be a .pdf file found on the Events Calendar under the date Monday, November 22nd, 2010. The practice test consists of 32 questions. For each question, page numbers in the book have been given to guide you to the area in the book that you will need to read and study to answer the question.
  • A VODCast of all of the solutions to the practice test will be posted to the Events Calendar under the date of Tuesday, November 23rd, 2010. It will be more than just answers. I will use the practice test as an opportunity to teach a deeper understanding of the concepts associated with each question.
  • On Wednesday, November 24th, 2010, the actual take home quiz will be posted on the Events Calendar as a .pdf file. You will need to print the quiz and complete it and be ready to turn in at the beginning of class, Monday, November 29th, 2010.
Below are links to four video resources that I found on the web that could be of use to you as you complete this independent unit of study.

Finally, you will have a true extra credit opportunity this week. You will be asked to download and use a molecular modeling software called Jmol. Use the link on Jmol to go to the site and download the software now if you want. I will have a VODCast available either Wednesday or Thursday of this week on how to install and use the software. Look back to the blog later this week on specifics of what you need to do to earn the extra credit.

I will be checking my school email periodically over the break, so email me if you have any questions. Also, you do have my cell phone number, so please feel free to call if you need any assistance.




Thursday, November 18, 2010

Chapters 8, 9, and 24 Review

Below this written is a key for all of the questions /problems presented in the review for the Chapters 8, 9, and 24 test. All of the concepts on the test are not covered by the review packet. I will list the topics not covered in the review packet so you can look at other materials from the unit of study. The test will consist of 35 multiple choice questions and 5 short answer questions. You will be supplied a periodic table (the one given for the AP Chemistry exam) and I will give you a electronegativity table, though one would not be supplied on the AP Chemistry exam. You will also be able to use a calculator.

I have supplied more information than what is needed in the answers to the key below. I was more in-depth than what would be needed on the exam because I wanted to use the study guide and key as one last teaching tool. When answering an AP Chemistry free response question: (1) Do exactly what is asked to do. (Draw a Lewis structure, etc.) (2) Make sure to compare and contrast if asked to do so. (3) Any term used in the answer should be defined.

WHAT TO STUDY
  1. Know how to define (non-polar) covalent, polar covalent, and ionic bonds and understand the mechanisms of how each is made.
  2. You need to know from memory all parent geometries, molecular geometries, and bond angles. Know the criteria for each.
  3. Know the concept of lattice energy and that the magnitude of lattice energy is dependent upon the magnitudes of the ion charges and the distance between the nucleus of both ions in the bond. For a large lattice energy, large charge magnitudes and small ion distances are needed. For a smaller lattice energy, small charge magnitudes and large ion distances are needed. L.E.=k(Q1Q2)/d.
  4. Know all criteria for hybridized orbitals. On a previous blog post, all of the criteria and applications were written out.
  5. Know how to determine the enthalpy (heat) of a reaction from the energy inputs (i.e. heat of sublimation, bond energy, ionization energy, etc.) and energy outputs (electron affinity, lattice energy). If energy inputs exceed energy outputs, a endothermic reaction will occur. If energy outputs exceed energy inputs, a exothermic reaction will occur.
  6. Know how to choose the most plausible Lewis structure based upon formal charge. Zeros are preferred and the more electronegative element should be a negative number is not zero. Also, all formal charges must add up to the total charge of the molecule.
  7. Know the basic concept of isomers. This is covered in its most basic form on page 1026 of your book at the very beginning of section 24.4. This concept is covered in the review from the year 1994, question #43. An isomer is a molecular formula that can have more than one Lewis structure that works for the number of atoms in the molecule. This is not to be confused with resonance structure, which is just the moving of a double or triple bond. This is completely different positions of atoms within the molecule with different types of bonds to achieve the different atom positions. I have given an explanation on the review.
  8. Know how to define and recognize a Lewis acid and a Lewis base.
  9. Know the rule to determine the coordination number of a Lewis acid is to double the oxidation (charge) number. The coordination number will be the number of ligands (Lewis bases) that will surround the Lewis acid (metal ion) in the middle of the complex ion.
  10. Know the types of hybridization for a metal that are needed for different coordination numbers.
  11. Know the basic naming system of complex ions.
  12. Be able to write a net ionic reaction for the formation of a complex ion.
















Monday, November 15, 2010

Correction to VSEPR Lab

The correction to the 2nd VSEPR lab has been made and is posted in the same place on the Events calendar as the original. The last slide was changed from sulfur monofluorine tetrahydride (SFH4) to iodine monofluorine tetrahydride (IFH4). Also, if the file for the Power Point becomes too large to send via email, please bring the file to me on a CD or a Flash drive. Please come and see me if you have any questions about the lab.

The question #5 from the Chapter 8 WebAssign has been removed due to difficulties completing the problem.

On Wednesday, you will be receiving an optional review assignment for the unit exam which will be this upcoming Friday, November 19th. I will try and have a podcast of the solutions posted so you can assess your comprehension of the material on the unit.

Friday, November 12, 2010

VSEPR Lab

You were given the VSEPR lab today in class. The lab will be due next Thursday, November 18th, 2010. The lab that you need to access is posted on the Events Calendar on the AP Chemistry web-site. VSEPR is an acronym for Valence Shell Electron Pair Repulsion. It is the repulsion of the electrons that create the geometric angles between the bonding and non-bonding ligands. Remember, non-bonding ligands repel more than bonding ligands. That is why the bond angles decrease as bonding ligands become non-bonding ligands within a particular type of parent geometry. Remember on the parent geometry trigonal bypyramidal, the equatorial bonding ligands transform to non-bonding ligands first because of the greater bond angles (120^o vs 90^0) allows for more space between the non-bonding ligands. (Non-bonding ligands repel more than bonding ligands.)

Molecular polarity - is a molecule symmetrical (same charge distribution all around the molecule) or asymmetrical (charge distribution is unequal around the molecule)? Symmetrical is a non-polar molecule and asymmetrical is polar. When you build your molecules, any difference in color for pipe cleaners used will cause the molecule to be asymmetrical, thus polar.

Please see me if you have any questions concerning the lab or concepts needed for the lab.

Thursday, November 11, 2010

Take-Home-Quiz and Hybridization Recap

Below are two images of Power Point slides that have the questions that need to be answered for tomorrow, Friday, November 12th, 2010. Please have your solutions / answers to the problems ready to turn in at the beginning of class.

I would like to go through a quick recap of hybridization for bonding.
  • A single bond always involves only a sigma bond. A sigma bond is between two hybridized orbitals or a hybridized orbital with a non-hybridized 1s orbital of a hydrogen atom.
  • A double bond always involves a sigma bond and pi bond. The pi bond originates from two non-hybridized p orbitals overlapping.
  • A triple bond always involves a sigma bond and two pi bonds.
  • Ligands are either covalent bonds or non-bonding electron pairs. A single covalent bond, double covalent bond, or triple covalent bond are all considered one ligand.
  • sp^3 hybridization is required when four ligands surround an atom. The hybridized orbitals can be used for sigma bonds or to hold non-bonding electron pairs.
  • sp^2 hybridization is required when three ligands surround an atom. The hybridized orbitals can be used for sigma bonds or to hold non-bonding electron pairs.
  • sp hybridization is required when two ligands surround an atom. The hybridized orbitals can be used for sigma bonds or to hold non-bonding electron pairs.



Saturday, November 6, 2010

General Information

The WebAssign is up for chapter 8.