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Q & A: electron as smeared cloud

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Most recent answer: 02/24/2015
Q:
Thank you for taking time to try and answer people's questions. I am still confused about the electron. I teach people about electrons and their configuration. One idea is that the electron behaves as a shmeary, three-dimensional, charged bit of possibility cloud... In Hydrogen we have one of those, in Helium two of those... On a water molecule Two Hydrogens share their cloudy charges with an Oxygen which then has extra electrons and creates a dipoled molecule... When I show a Hydrogen atom to a group of 7th graders and then go to describe its electron should I try to describe is as a shmeary cloud of charge somewhere about 10 ft from my grain of salt sized nucleus? Do you have a more updated visualization that I could share with my students?Thanks very much!
- David (age 29)
Philadelphia, PA
A:

What you're teaching sounds very nice, more accurate and sophisticated than what is usually taught. That cloud for hydrogen in its ground state extends out from the nucleus as you say, but is actually densest right in the middle.

This site http://www.falstad.com/ has some great applets for picturing the behavior of those smeared wave functions. I don't see any on it for molecules like water with three atoms, however. There is a large collection of static images you could use here: https://www.google.com/search?q=visualizing+molecular+wave+functions&espv=2&biw=1370&bih=603&tbm=isch&tbo=u&source=univ&sa=X&ei=Y6nwVIyfE82xyQS964F4&ved=0CD4QsAQ

‚ÄčIf your students would like to see real evidence for the smeared-out wavy behavior of electrons, these scanning tunneling microscope pictures of metallic surfaces are great: http://researcher.watson.ibm.com/researcher/view_group_subpage.php?id=4252. Don Eigler, who developed this beautiful technique, was an undergrad who liked to skateboard barefoot around the physics building at UCSD when I was a grad student there.

Mike W.

p.s. You may be amused by this old thread: http://van.physics.illinois.edu/qa/listing.php?id=28187.


(published on 02/24/2015)

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