Posted in Education, Physical Chemistry, Science Education, Spectroscopy, UV-VIS-NIR, working problems

Spectrum of a Particle in a 1D Box

It is safe to say that every physical chemistry course teaches the Particle in a Box problem as an introduction to quantum mechanics. I have taught it also in my course for years.

I have been bothered for years, however, by the fact that the text books stop after solving the Schrodinger equation. All of them that we have surveyed do this. McQuarrie, Atkins, Engel, Levine, etc.

This is a shame because we can’t detect the energy levels by themselves. Quantum theory was invented to explain spectroscopy. So why not take the 1D Particle in a Box (1DPB) problem all the way to a simulated spectrum?

At SHSU, we do.

Here are three lectures that explain what I do with the Particle in a Box.

(Be patient with the Kahoot quizzes and end of class Q&A. Feel free to skip ahead, or try to answer the questions in your own mind to see how you do! To find all my Kahoot content search for my username chem_prof on Kahoot. I have Quantum, Thermo, and Forensic Chem Kahoots.)

Lecture 1 – Managing the Messy Mathematics

This lecture takes the spectrum of a 1DPB apart to show what pieces of the spectrum are explained by quantum theory.


Lecture 2 – The Schrodinger Equation

This lecture is the traditional presentation of the 1DPB problem – normalizing the wave functions and solving for the energies via the Schrodinger equation.


Lecture 3 – Spectral Transitions and Spectral Assignments

This lecture discusses spectral transitions, the transition moment integrals and the transition equation which tells us about the spacing of our spectral lines. The transition equation also tells us about the quantum system if we begin with an experimental spectrum and assign the quantum transitions.


What are your reactions to this approach? I’d love to hear from you in the comments section. I am preparing this material for a book for students to read in the summer prior to taking pchem. I think it will greatly help to get them thinking about our quantum world early and often.

Happy Pchemming!

Darren Williams

Posted in EXCEL BOOT CAMP, Science Education

Charting Pro Tips in Excel

This installment of the Excel Boot Camp covers three topics.

  1. Cell block navigation – No, this is not related to Huntsville, Texas. 😉
  2. Efficient ways to select data.
  3. Creating XY Scatter charts

Cell Block Navigation

For small blocks of data – tables that fit on one screen – the mouse is fine. But for LARGE sets of data like an FTIR spectrum that has over 2000 data points, navigating around the data set with the mouse is stupid. (Yes, I said it.)

You can navigate within a block of cells containing data in the following manner:

  • Arrow keys move the cell selection one row or column at a time.
  • “Ctrl + arrow” moves the cell selection to the far right, far left, top, or bottom of the block of cells according to the arrow that was used.
  • “Ctrl + Home” moves the cell selection to cell “A1” – the topmost corner of the sheet. This is very handy.
  • Ctrl + PgUp and PgDn change the sheets. (That’s ripe for a meme.)
  • “Ctrl + End” moves the cell selection to the bottom-right corner of the data on a sheet.

Selecting Data

Adding the Shift key to the above sequences allows you to select large chunks of data. This is necessary for EFFICIENTLY charting what you want to chart.

Say I had a data set with an x-values column and 15 y-values columns. And  furthermore, I only want to plot the first three y-columns against the same x column.

  1. I left-click the x-value column header.
  2. I press and hold Shift.
  3. I tap the right arrow 3 times.
  4. I add the Ctrl key so that Ctrl and Shift are BOTH pressed.
  5. I tap the down arrow, and voila! A block of the x-values and three columns of y-values are selected and ready to chart.

Charting Pro Tips

Since this is so visual, I’m going to punt and say “Watch the video…


I welcome your comments, likes and subscribes. You know the drill.

Happy pchemming!


Posted in EXCEL BOOT CAMP, Science Education

Anchoring Cells in Excel

The first Excel Boot Camp topic is on anchoring cells. Newcomers to Excel must master this skill early on to be successful.

To enter formulas into Excel, simply click in a cell with the mouse, type “=” and enter the formula. Notice that you can use references to other cells in your formulas, and THAT is why spreadsheets are so useful.

Spreadsheets are NOT just tables of numerical values. They are complex interrelated formulas that change output when the input changes.

Spreadsheets are also incredibly visual which is why I favor them when teaching the applied mathematics related to physical chemistry.

So back to the main topic.

The dollar sign symbol “$” is the anchor. If you create a cell formula in cell B5 for a linear equation such as “y = mx + b” using cell references, it might look like this. “=B1*A5+B2”

B1 is the slope value at the top of the page, B2 is the intercept value at the top of the page, and A5 contains the x values for the equation. If you copy this formula down for several x values, the formula in B6 will have a slope of B2 and an intercept of B3. This is bad! The “constants” have been pulled down by when the formula is copied down the column.

The relative cell references act like boats that can be pulled along wherever the formula is pasted. But if the formula contains a constant cell reference you need to anchor that boat on a specific cell.

Use the dollar sign symbol to anchor the cell references so that the formula in B5 is “=$B$1*A5+$B$2”. Now, the formula will use the slope in B1 and the intercept in B2 no matter where it is pasted.

And that’s how you anchor cells.


If you are typing your formulas into Excel, you are prone to make mistakes! Use the mouse to select the cells for your formulas. When you click on a cell that should be anchored, hit the function key “F4” at the top of the keyboard. This automatically adds the dollar signs to the cell reference. Sometimes you only want to anchor the column, or the row, so hit “F4” multiple times, and the anchoring will cycle through all the options.

We learn by doing, so watch the video and try it yourself!


Posted in D L Williams, Education, EXCEL BOOT CAMP, Science Education

How to EXCEL in PCHEM?

I have begun a new tutorial series on Excel I’m calling my EXCEL Boot Camp.

Why host an EXCEL Boot Camp for PCHEM?

I’m glad you asked


Many of my students have never used EXCEL. Years ago, I added videos to the lab materials showing them how to complete the many data analysis tasks in Excel, but these were very cook-book in nature. The students were successful in following the recipe, but if they made any small mistakes along the way the process dragged on, consuming the whole FOUR-HOUR lab period (or longer).

In this situation, when it came time for the student to answer some simple and basic questions about the SCIENCE behind the Excel data analysis, they were unable to do so.

Therefore, I am adding some Excel tutorials that are skills-based. This will train the students in the useful spreadsheet skills so that they can bring them to the data analysis exercises and fully participate in the SCIENCE.

The Lessons will be added to this blog as they become available on YouTube. You can subscribe here and on YouTube to be notified when new content is posted.

Happy pchemming!


Posted in Contact Angle, Critical Solution Temperature, D L Williams, DSC, Education, Forensics, FTIR, Hansen Solubility Parameters, LIF, Physical Chemistry, Raman, RER, Science Education, Solubility, Solvent Blending, Spectroscopy, Thermal Analysis, UV-VIS-NIR, XPS

PCHEM and Forensic Chem Lecture Videos

I frequently have seniors who want to revisit the concepts in pchem sit in my 8AM lectures the year after they have had my course. It’s a privilege to have them and an encouragement to see their natural curiosity in action. They seek to firm up their understanding of the quantum world and how we interact with it (i.e. spectroscopy).

In the fall of 2017, I put these students to work videoing the lectures and posting them on the Physical Chemistry at Sam Channel. These videos are essentially raw footage of lecture. The videos could have been greatly improved by adding in the PowerPoint Slides, captioning, cleaning up the audio, and cutting out my “ums” and “uhs”. But these volunteers did not have time to do that, nor did I. I had a CLEANING WORKSHOP to plan and execute!

CHEM 4448 – Physical Chemistry 1
– Quantum Mechanics and Spectroscopy


CHEM 4449 – Physical Chemistry 2 -Thermodynamics


CHEM 4380 – Forensic Chemistry

The students appreciated the fall lecture videos so much, there was a great amount of interest in capturing the Forensic Chemistry Lectures. So we created a Forensic Chemistry at Sam Channel, too.


The lecture playlist is only one piece. Jessy also created other playlists of videos on the Forensic Chemistry at Sam Channel that should interest Forensic Science and Forensic Chemistry students and enthusiasts. She performed these tasks as an SHSU Honors Contract for the course – an activity that supplements the material for the student and enhances the skills that they take away from the course.

Thanks to the Student Team!

Even raw footage must be stitched together, uploaded, described, tagged, and set up on YouTube. This takes TIME and time is a valuable commodity for our chemistry majors.

I thank William Fernandez for videoing CHEM 4448 and CHEM 4449. His videos were so well-received by the students that Jerome Butler decided to sit in and video my Forensic Chemistry course CHEM 4380. Thanks Jerome!

I thank Matthew Peavy for producing the videos for CHEM 4448 and CHEM 4449, and for uploading them. I thank Jessy Stone for producing and uploading the CHEM 4380 videos for Forensic Chemistry.

You students who are willing to go beyond the minimum give us hope for the future.

You people in industry and in graduate programs, hire these students! You won’t be sorry!


Posted in Education, Physical Chemistry, reading science, Science Education, working problems

How to Teach Yourself

How do you teach yourself a new skill? How do you learn a tough subject? (like pchem?) I’m glad you asked. Here are my tips and tricks specifically focused on pchem survival (but applicable to life in general).


1. Don’t be afraid! (and that’s an order!)

Thousands have been down this road and they were in your shoes back then. You may have to shore up some mathematical deficiencies and look up some vocabulary, but these tasks are obvious to you as you go along. None of this affects your value as a person. But do you have the drive to re-learn what you have forgotten and dig into what you don’t know yet? Decide now! This is not a technical question. It is a heart question. Your answer to this question will determine your future as a productive team member after graduation.

2. Do the tutorials.

Every book has example problems in the text. Every coding site has tutorials. Even Excel has example data sets in its help files to show you “how it is done”. Do the tutorials.

3. Read the text with a pencil NOT a highlighter.

Write in your book margins. Rework math proofs in your problems notebook. Unless the material goes in your eyes, rattles around in your brain, filters down your arm, and out through your pencil, then you haven’t comprehended the material. Highlighting is nothing but self-deceptive Arts and Crafts.

4. Keep a problems notebook.

Do all your problems in a composition book. It is bound and sturdy. It will last much longer than a spiral notebook. Thirty years from now, you can be amazed at how bad-a$$ you were in college when you look at the math problems you did!

AND you can use it to shame your college-aged kids when they complain that their college prof won’t just upload the homework concepts directly into their brain-chip.


If you would just use UNITS on your numbers you would catch 99% of your errors. I can’t scream this loudly enough! Units, units, UNITS! Use them, or fail. It’s on you.

“But they take up space. They take time. Whaa Whaa Whaaaa” Look at the photo uploaded with this post. There is NO way to catch all the powers of 10 that jump around in that problem without using units.

6. Pro-tip: Be Disciplined

“The scheduled task gets done”, said my father.

If your homework time is not scheduled, then it will not get done. If you are not using the phrase, “I can’t, I have PHCEM homework to do.” Then you are not learning pchem.

If you want to learn piano or guitar and you don’t schedule practice time, then I don’t want to hear you play. It is the same with sports. If you don’t schedule practices, then I’m not buying a ticket to your game.

Put LEARNING on the calendar, not just TESTING.

—Here endeth the lesson.

Posted in Education, Physical Chemistry, Science Education

Same Behavior, Same Results

T-minus one week and counting…

first class day

We start up the semester at Sam Houston State University one week from today. So I thought I would address the students at SHSU in general and the Physical Chemistry students in particular.

What are YOU going to do differently this year to ensure you improve performance, retain knowledge, and cultivate character?

Even the 4.0 student can improve in these areas. Begin by writing out your goal. It might look like:

  1. Make straight A’s this semester.
  2. Not get behind in my classes, job, club officer position, and family commitments.
  3. REALLY learn the material so that I can draw on my knowledge in future classes and jobs.

Whatever the goal is, do not forget to do this next important step.

Think back to last year. Identify what kept you from achieving this goal last year. Be specific. Was it a habit? a video game? a TV show? a friend who dominated your time? a student organization?

Now, change it. If this activity, person, or situation pulled you off your path to success, then either change it or change your path. You cannot follow two paths.

You cannot do everything.

Now, is the time to plan. If you are a chemistry major, especially, now is the time to commit yourself to hard work, problem sets, reading the text, and a smaller social agenda.

In the future, you will be hired based upon your chemistry abilities, not how many activities you were in. Be the best, most knowledgeable graduate you can be, no matter what your major.

It starts today.