The chemistry of silver and the process in which silver becomes tarnished is explored. Take a new look at an old JCE Classroom Activity.
Flinn Scientific has a great elearning video series. Many of the videos have master teachers demonstrating some great labs and techniques that they do in the classroom. A general theme in many of the videos seems to be combining demonstrations, labs, calculations and lab practicals. The nice part about what occurs is that for whatever concept the students are doing, it is not enough to come up with an answer on paper. They have to use that answer for a prediction and then see if they are correct actually checking and manipulating material. This idea has added a new dimension to my classroom. Students who are tired of "pen and paper" work now get to get up and use their answers to mass something or find the volume of something and see if they are correct. I have tried to add more of these to my lessons.
As we pilot new laboratory activities in the classroom, my students and I are in constant dialogue. Not only do they leave feedback at the end of each lesson (what did you learn, what was your favorite part, what was you least favorite part), but we talk throughout the experiment. Recently our discussion was focused on the questions.
In my IB Chemistry class, my seniors were finishing up independent investigations for their Internal Assessment a few weeks ago when something cool happened. One of my students was using silver nitrate and potassium chromate for a titration. This is notable to the story here because the endpoint is marked by the formation of silver chromate as a precipitate, with a deep reddish color. I overhead the student showing his reaction to another student, with both of them commenting on the cool colors involved.
First, I would like to thank all those who commented on my last blog. For the record, I was wrong. Initially I looked at Linus Paulings early papers as he worked on electronegativity. Much of the work focused on connecting the concept to bond energy. There were some great comments posted to the blog. Probably one of the best was explaining how the concept of electronegativity presents a model for bonds. It is not an observable quantity. This really helped me explain it better to my students. As the commentor posted, all models have limitations. Second, the person commented that in Linus Pauling's General Chemistry book published in 1970 (Dover Publishing) that he does indeed talk about the differences in electronegativity to discuss a type of ionic and covalent character. I stand corrected.
This year in the midwest United States, winter has been a fickle friend. I haven’t seen the same amount of snow or ice as in recent years, but I still made sure I was prepared for it at our home. I went to my local big box hardware store in December and contemplated buying rock salt (NaCl), and NaCl/calcium chloride mixture, or just calcium chloride. Growing up my dad had switched entirely to calcium chloride because it was less damaging to the brick pavers leading to our porch and backyard. In fact, calcium chloride is generally much safer toward plants and soil than NaCl. Even though calcium chloride is much more expensive than rock salt (it was about twice the cost for 10 pounds more), that what’s I chose. Why?
The Biennial Conference on Chemical Education (BCCE) will be held at the University of Northern Colorado in Greeley, CO from July 31 through August 4, 2016. This is an excellent professional development opportunity for high school and college chemistry instructors. You still have time to submit an abstract to present. Presentations are generally 20 minutes in length.
In my high school chemistry class, a unit we cover is that of atomic structure. In particular, given an elements symbol, mass number, atomic number, and charge, the objective would be for the student to determine the atoms number of protons, neutrons, and electrons. I have several apps/program suggestions that can be useful for this purpose.