Chemistry 221

CH 221Z Announcements

October 31, 2025

Items Due During Week 7:

Section L1: Due in Recitation on Monday, November 3 at 1:10 PM in AC 2501
• The "Lewis Structures" lab
• Problem Set #5 (self corrected using the recitation video)
• We will take Seminar Self Quiz #5 and Quiz #5
• Bring a printed copy of the Valence Bond and Molecular Orbital Theory to recitation

Section L2: Due in Recitation on Tuesday, November 4 at 8:30 AM in AC 1303:
• The "Lewis Structures" lab
• Problem Set #5 (self corrected using the recitation video)
• We will take Seminar Self Quiz #5 and Quiz #5
• Bring a printed copy of the Valence Bond and Molecular Orbital Theory to recitation

Section L3: Due in Recitation on Wednesday, November 5 at 1:10 PM in AC 2501
• The "Lewis Structures" lab
• Problem Set #5 (self corrected using the recitation video)
• We will take Seminar Self Quiz #5 and Quiz #5
• Bring a printed copy of the Valence Bond and Molecular Orbital Theory to recitation

Section L4: Due in Recitation on Friday, November 7 at 1:10 PM in AC 2501
• The "Lewis Structures" lab
• Problem Set #5 (self corrected using the recitation video)
• We will take Seminar Self Quiz #5 and Quiz #5
• Bring a printed copy of the Valence Bond and Molecular Orbital Theory to recitation

All Sections:
• Start studying the material in Chapter 5.
• This upcoming Friday (November 7) is the last day to drop (or change the grade status of) individual classes at Mt. Hood Community College. You can find more information using this link.
• Veterans Day is commemorated at MHCC on Tuesday, November 11, and Mt. Hood Community College will be closed. Section L2 of CH 221 will have recitation and a lab on Thursday of week 8.

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This week we investigate the reasoning used to justify the Lewis structure and VSEPR, i.e. the theories of how molecules form bonds. We will explore the two relevant theories, namely Valence Bond (VB) Theory and Molecular Orbital (MO) Theory, and they both offer benefits to modern chemists (as well as some drawbacks.) Please contact me if you have any questions, ok?

Here's what is happening in week 7 of CH 221:

• Special Note: Tuesday, November 11 is Veterans Day, and Mt. Hood Community College will be closed. Section L2 will have recitation and lab on Thursday, November 13.... more information coming soon.

• Explore the material in Chapter 5. There are several tools to help you learn the material.... they include:
  • Read Chapter 5 in the textbook
  • Watch the Complete Lectures for Chapter Five (found here: Part I, Part II)
  • Lecture videos for Chapter 5 will be found on YouTube and as a Podcast
  • Chapter Guide Five (online learning materials for Chapter 5) might be helpful
  • "Mini video lectures" ("Screencasts") can be found in the Videos page for CH 221 under Chapter 5.
  • The Concept Guide for Chapter 5 and other relevant handouts could prove useful.
• Due: Problem Set #5 which covers problems from Chapter 5.
  • Use this link to get the Fall 2025 version of problem set #5 and use this link to find the recitation video which you can use to self correct your work before turning in to the instructor.
  • Practice Problem Set #5 might be of help while completing problem set #5; answers are included at the end of the document.
• This Week: Seminar Self Quiz #5 and the (actual) Quiz #5
  • All quizzes (Seminar Self Quizzes and actual Quizzes, as well as midterm exams and finals) are closed book / no notes allowed. You cannot use a cell phone or computer; you can have a dedicated calculator and a periodic table (which I will provide) only.
  • First, take Seminar Self Quiz #5. You will have 20-30 minutes to complete the quiz, and afterwards we will self correct the Quiz as a class before turning it in. If you are late, or do not attend recitation for any reason, your score will be a zero on the Seminar Self Quiz.
  • After taking the Seminar Self Quiz, you will take the actual Quiz #5. Quiz #4 will take about 30 minutes and consist of several 'show your work' questions. Turn in the quiz when done (I will pass back any corrected work I have for you at this time.)
  • Sample Quiz #5 (answers at the end) might be useful to help you prepare and study.
• Due: The Lewis Structures lab
  • Bring the completed lab with you to recitation
• Start: The Valence Bond and Molecular Orbital Theory Lab.
  • Bring a printed copy of the Valence Bond and Molecular Orbital Theory lab with you to class.
  • Here is a video which shows what the lab will be like, offer hints, etc.

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Here's a preview of what's going to be happening during Week #8:

• Special Note: Next week Tuesday, November 11 is Veterans Day, and to commemorate it, Mt. Hood Community College will be closed on Tuesday, November 11. Section L2 will have a lab and lecture on Thursday, November 13 at 8:30 AM (no lecture this week.)

• Midterm Exam II
  • This midterm exam covers problem sets #4 and #5 (essentially Chapters 4 and 5.)
  • The midterm will have 12 multiple choice questions and four short answer questions. You will not need a scantron to complete the exam, but you will need to mark your answers clearly on the exam itself. You will have 90 minutes to complete the midterm exam.
  • The midterm exam will be closed book; no notes are allowed. You will be able to use your calculator and a periodic table (which I will provide.)
  • The first and last pages of the exam deserve some comment. The first page of the midterm will include an integrity statement that you will be required to sign. Signing the integrity statement implies that you have not received (and will not be giving) any information on the midterm exam to others that might imply cheating; a failure to sign the integrity statement grants an automatic score of zero, so make sure the first thing you do is to sign the statement. The last page of the midterm exam will be a scoring page which will be filled out by the instructor when the exam has been graded; you do not need to complete anything on this page. An example of the integrity statement and grading sheet (for Exam I) can be found here: link

• Midterm Exam II details by section of CH 221:
  • Section L1 will take the midterm on Monday, November 10 at 1:10 PM in AC 2501.
  • Section L2 will take the midterm on Thursday, November 13 at 8:30 AM in AC 1303 (date different due to Veterans Day.)
  • Section L3 will take the midterm on Wednesday, November 12 at 1:10 PM in AC 2501.
  • Section L4 will take the midterm on Friday, November 14 at 1:10 PM in AC 2501.

• To Study and Prepare for Midterm Exam II:
  • Watch the Complete Lecture of an Exam Review for the second Midterm Exam here: Midterm Exam II Review
  • Lecture videos for the Exam Review for the second Midterm Exam will be available on YouTube and as a Podcast.
  • A sample exam is available on the Chemistry 221 website under Quizzes and Exams.

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Also happening during Week 8 in CH 221:

• Due: The Exam Prep II worksheet.
  • This week we will not have a problem set, seminar self quiz or regular quiz, but you will need to complete the Exam Prep II worksheet.
  • The Exam Prep II worksheet consists of several problems followed by the answer; your goal will be to 'show your work' (in detailed steps) how to go from the question to the final answer. If you have questions on how to do this, you can reach out for assistance to the LSC/AVID center or the instructor.
  • The Exam Prep II worksheet will be due at the time of your midterm exam I.
• Due: The Valence Bond and Molecular Orbital Theory Lab.
  • Bring the completed lab with you to recitation
• Start: The Empirical Formula Lab.
  • Bring a printed copy of the Empirical Formula lab with you to class. Bring your safety goggles - they are required this week!
  • Here is a video which shows what the lab will be like, offer hints, etc.
• Heads up: Next week is the week of Class Presentations on your reserved element. You will give your (less than five minute) presentation to your lab group and turn in the final Class Presentation paper. More information can be found using this link.

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