professor holding atom models

Chemistry 105/106

Diagnostic Exam

Taking Introductory General Chemistry I (Chem 105) in the fall? You need to take the online diagnostic exam!

All first-year students registering for Introductory General Chemistry I (Chem 105) in the fall are expected to take the online chemistry diagnostic exam between June 10, 2019 and July 5, 2019.

The objectives of the online diagnostic exam include the following:

  • Assess if Chem 105/106 is the optimal course sequence for you, so you can obtain helpful placement advice from us.

  • Identify students who may benefit from supplementary resources at WU, such as extended recitation sections and peer-led team learning (PLTL) study groups. Recommendations regarding extended recitations will be given to you by late August.

You will need your six-digit WU student ID number to access the diagnostic exam, but no password is required. If you have questions about your student ID number or any problems logging onto the website please, please contact Dr. Jia Luo via e-mail (JLUOA@WUSTL.EDU) or phone (314-935-4163). Contact by email is preferred.

Note that each student has only one attempt to complete the diagnostic exam. We recommend you first read the instructions for taking the diagnostic exam before attempting the exam.

 

DIAGNOSTIC EXAM LOGIN

Required Materials

Textbook

Chemistry: The Science in Context (5th edition) by T. Gilbert, R. Kirss, N. Foster, S. Bretz, and G. Davies. The electronic version (e-text with access to online animations) is required. A hardback version is also acceptable for supplementary purposes. There will be two copies of the 5th edition text on reserve in the Chemistry Library after the fall semester starts.

Calculator

Only the following models of electronic calculator will be allowed during quizzes and exams: TI-30 XS Multiview (preferred 4-line model), TI-34 Multiview (preferred 4-line model), TI-30Xa (acceptable 2-line model), TI-30X IIs (solar 2-line model). Allowable calculators must be four-line or two-line, non-programmable, non-graphing calculators. This policy will be strictly enforced with no exceptions. Acceptable calculators are available from the WU bookstore as well as Amazon, Walgreens, Staples, Office Depot, and other office supply stores.

Online Homework

In Fall 2019 and Spring 2020, Chemistry 105 and 106 will not use an online homework platform.

Recitation Subsections

Every student who registers for Chemistry 105 must register for a lecture section that meets MWF, as well as a recitation subsection that meets on Thursdays. You will find information below to help you choose which style of recitation might be best for you. Even though all recitations cover essentially the same material and example problems, there will be two different formats offered.  You should choose the recitation format that you feel best suits your approach to learning and perceived level of preparedness for Chemistry 105.
 

Recitation Types

Classic (regular) format: These recitation sections are 1 hour in length.  The format includes a quiz during the first 15 minutes of class.  Following the quiz, a brief summary of the week’s main lecture topics is presented and challenging practice problems are worked for the remainder of the class period. A trained graduate Assistant in Instruction (AI) leads this problem-solving session.

POGIL (guided-inquiry) recitations: These recitation sections are 1.5 hours (30 minutes longer than the regular recitation sections).  This format also includes a quiz during the first 15 minutes of class.  Following this quiz, and a brief summary of the week’s topic by the graduate AI, students will work in small, structured groups on guided-inquiry problem sheets that have been written specifically for Washington University Chemistry 105 topics.  These problem sheets are designed to help develop self-teaching and problem-solving skills, as well as to call attention to crucial concepts discussed in lecture through exploration and analysis of challenging example problems.

The custom-designed exercises and selection of problems include an emphasis on conceptual aspects of the topic.  This format is designed to help you gain a deeper understanding of the concepts underlying problems.
 

Comparison of Regular and POGIL Recitations

Although both regular and POGIL recitations cover the same topics with the same practice problems in every weekly session, POGIL worksheets break down each problem into several guiding questions to lead students to think through the concepts and solve the problem in a stepwise manner.

Example Problem for a Specific Topic: Lewis Structure

Problem: Draw the most-preferred Lewis structure for the neutral molecule HOCO2H. Record the total number of valence electrons on the line indicated. Label all non-zero formal charges directly on each atom.

In a regular recitation, after a brief review of the topic “Lewis Structures,” this problem would be presented as written. Students would then be asked to work the problem either individually or with other peers. The AI would circulate around the room to answer any questions while students first attempt the problem. Finally, the AI reviews the problem on the board and shares the correct answer to ensure understanding.

In a POGIL recitation, the worksheet addresses the same problem in a stepwise manner as shown below:

  1. Count the number of valence electrons contributed by all atoms in the molecule. Record your answer.
  2. Establish atomic connectivity.
  3. Connect adjacent atoms with electron-pair bonds.
  4. Add lone pairs to complete octets on the outer atoms.
    • Which of the following drawings show(s) acceptable placement of lone pairs and/or remaining electrons? (Given several options.)
  5. Add any remaining electrons as multiple bonds or lone pairs on the central atom.
  6. “Push” electrons to obtain octets, if possible.
    • How would you “push” electrons from the answer you chose in step 4, in order to obtain a complete octet for all atoms (except H)? Draw arrows to show how electrons are pushed and draw the final structure.
  7. Determine formal charges.

As you can see, in both recitation sections students ultimately draw the Lewis structure of HOCO2H.

However, when answering the POGIL guiding questions, students are prompted to address key concepts involved in the problem and guided through the problem-solving process. The group work format provides a structured environment for students to discuss with their peers. By articulating their opinions and communicating with peers using scientific language, the students’ understanding of certain concepts becomes polished. In general, students’ confidence and communication skills are strengthened through practice and discussion of the problems.

Choosing the Best Recitation Style for You

Research studies show that the POGIL-style recitation is beneficial for most first-year students, especially in the early times of developing self-teaching, self-learning, and problem-solving skills. To decide whether a regular or POGIL recitation will benefit YOU the most, consider the following questions:

  • Do you think you would benefit more from spending 30 minutes longer in recitation every week?
  • Do you think you would benefit more from a guided approach to the problem-solving process?
  • Do you think exchanging ideas with your peers in a structured environment would help solidify your understanding of a topic?

If you answered yes to all of these questions, then the POGIL-style recitation is recommended for you.

If your answer to one or more of these questions is no, you may want to consider enrollment in a regular recitation. No matter what style you choose, everyone has access to the same information. All students are encouraged to check out the POGIL worksheets, which are available through the course webpage at the end of each week.

Course Descriptions

The Introductory General Chemistry sequence (Chem 105/106) is designed for students who have only one year of high-school chemistry or physics OR students who would benefit from a review of chemistry fundamentals.

Introductory General Chemistry I (Chem 105)

This course traces the development of chemistry from early atomic theory to modern descriptions of structure, bonding, and intermolecular interactions. Over the course of the semester, the students learn how macroscopic observations of stoichiometry, chemical reactions, the properties of elements and compounds, and chemical periodicity developed into the microscopic understanding of molecular structure and bonding. The semester begins with fundamentals related to stoichiometry, chemical reactions, solution chemistry, and gas properties, with an emphasis on quantitative problem solving. The octet rule, Lewis structures, and valence-shell-electron-pair repulsion (VSEPR) theory are then introduced as early efforts to describe the stability and structures of molecules. The localized electron model (LEM) and molecular-orbital theory (MOT) are next described as modern descriptions of chemical bonding. The course concludes with intermolecular forces such as hydrogen bonding and van der Waals interactions.

Prerequisite skills include the following: proficiency in algebra, familiarity with solving simple quantitative word problems, and familiarity with unit analysis.


Introductory General Chemistry II (Chem 106)

This course covers chemical equilibrium, thermodynamics, and kinetics at a fundamental level, with an emphasis on in-class problem solving. Gas-phase reactions, heterogeneous (multi-phase) reactions, acid-base reactions, and solubility equilibria are introduced first. Chemical thermodynamics is then taught in its relation to chemical equilibrium. The course finishes with chemical kinetics and rate laws. The content is similar to that in Chem 112A, but advanced applications are omitted to allow more in-class guided active learning.

Prerequisite skills include the following: proficiency with algebraic manipulation of equations and relationships, familiarity with solving multistep quantitative word problems, familiarity with unit analysis.

Knowledge-based prerequisites include the following: familiarity with (1) stoichiometry, balancing chemical equations, determining the limiting reagent; (2) compounds and chemical formulas; (3) unit conversions, including grams to moles; (4) determining molarity and dilution calculations; (5) states of matter; (6) fundamental acid/base reactions in water; (7) writing net ionic equations; (8) balancing redox reactions; and (9) the ideal gas law and Dalton's law of partial pressures. All these prerequisites are provided by Chem 105.