Teach Fzx - Nobody Knows Nothin about the Atom

For many years, my Physics students have taken a quick quiz just before electrostatics:

"Sketch and label and atom and its parts.  Use a modern model.  Be specific and ask no questions"   (The "ask no questions" clause was added after the class questions were leading more students to the correct answer.)

Keeping in mind that their first exposure to atoms is in primary school and that they study atomic theory again and again - earth science, biology, and chemistry - here are the results for my 60 to 100 Honors Physics students for each of the past years.

The Good News:

60-75% basically correct - protons and neutrons make up the nucleus.  electrons doing something outside.

This percentage seems to have improved over the years.  Perhaps this improvement is because there are more fans of "The Big Bang Theory" in my classes.  Hopefully it is because the chemistry teachers know the results of this quiz and have taken steps to emphasize certain concepts.

They even sketch one or two electron cloud models every year!

http://goo.gl/JhBcZP

The Bad News: The bad answers from most egregious to least. (25-40% )

1 to 5 - CELLS! - cell wall, cytoplasm, mitochondria, nucleus all labeled (2014 is the only exception to date)
1 to 5  - blank papers - IDK counts as blank
5 to 10 - circles labeled "atom" sometimes accompanied by a smiley face.
1 to 5 - with protons orbiting the nucleus or some such nonsense.
5 to 10 - with missing parts or labels - no neutrons or no protons or no nucleus.

More Bad News:

Today I asked the class "How big is the nucleus compared to the atom?"  I surveyed the first class individually and asked publicly for their answers.  The two basic answers were:

(90%) "The nucleus takes up most of the volume of the atom"
(10%) "The nucleus is a really small part of the atom"

For the second class, I modified the question to force them to give me a size fraction.  All the students except one gave a nucleus to atom size fraction from 1/10 to 1/2.  The exception was the lone student whose answer was one trillionth.

The third class seems to be the smartest.  Or perhaps they are the ones who overhear the discussion from earlier classes and discuss it themselves.  About 30% of those in attendance proposed fractions smaller than 1/1,000 but there were also two answers of 3/4 and 4/5.

Since the actual diameter of the atom is about 100,000 times larger than that of the nucleus, you can cube that for the volume ratio (1,000,000,000,000,000 = 1 x 10¹⁵ = one quadrillion).  Most answers were way off.

I then asked them about "Rutherford's experiment with ... foil."  Multiple students were immediately able to supply the missing "gold" in every class and many nodded vigorously when asked if they recognized the name of the experiment.

But as Richard Feynman's says of his father, "He knew the difference between knowing the name of something and knowing something."

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