Epic Way to Teach the Gold Foil Experiment
In one of my college classes, I had to teach a “mini lesson” to a group of math and science majors, soon to be teachers. I knew that this was going to be a somewhat difficult task because my high school students were going to have a bit more background knowledge than a math major would, so I aimed to keep my mini lesson super basic with some Atomic Theory.
Squishing this all together, I decided to do a mini lab on Rutherford’s Gold Foil Experiment for essentially people who knew nothing. It morphed later into a really good lab, that required some thought from my students. So we know that the Rutherford data shows that most of the alpha particles went through the gold foil, a few made weird turns/deflections, and a few bounced almost straight back. The key was finding a way to create a visual for exactly that, which was hard to do. But I did it. And here it is:
Rutherford Model for High School
You first need to make the model. This consists of a hula hoop, to represent a gold atom (you know a hula hoop is mostly empty space!) I also took a styrofoam ball and hung it inside the hula hoop using a string. This really could be any ball (mine is actually decently large) and this represents the nucleus of the atom. The styrofoam is just easy to put in the model since you can stick it with popsicle sticks to tie the string to. You’ll also need some ping pong balls to represent the alpha particles. You could totally use balls of scrap paper too!
The fun part of this lab comes next. You “voluntell” a student to collect data, and all the other students are given a ping pong ball (alpha particle) to launch at the model (which I’m usually holding since I can’t stand it up, or hang it from my ceiling).
Feel free to change up the language but data is collected as follows:
- A “miss” is when the ping pong ball goes straight through the hula hoop
- A “hit” is when the ping pong ball hits the styrofoam ball (alpha particle hit the nucleus and bounced back)
- A “deflection” is when the ping pong ball hit the hula hoop and “made a weird turn”
Now obviously, Rutherford’s Gold Foil Experiment had millions of alpha particles for his experiment, and my students use around 100 (each student gets 4 or 5 alpha particle launches depending on the class size) ping pong balls, so we work in percentages of course. And our data has never looked anything like Rutherford’s – AND I LOVE IT.
The Validity of Models in Science
This gives us a gateway to talk about the validity of models. Models are good but not great. We talk about the relative size of the “alpha particles” and the “nucleus” and the factor of having different students throw the ping pong balls. Considering I teach this lab right around the time that they fully understand the parts of a lab report, it gives them so much fuel for writing their first “really good” one. Especially after this class discussion, the kids are eager to showcase their writing and their evaluations of the experiment and compare data. They particularly enjoy the conversation that “bad science is good science” in that null results are still results.
Rutherford’s Gold Foil Experiment simulation is certainly their favorite lab up until we do the flame test lab (which is my personal fave). The idea of throwing things “at” their teacher always gets them excited. I’ve taken a few ping pong balls to the face over the years, but it never hurts and it’s something we can all laugh about. If you’re interested in getting your data a little more accurate, you can have them throw the ping pong balls with their eyes closed. That can usually get to be pretty funny as well.
I hope you and your students enjoy this lab activity and this opens up a world of conversations in lab reporting, validity of models, and accuracy of data.
