Atomic Models

Evidence-based theories on the structure of atoms have been around since the early 1800s. Dalton’s billiard ball model was the first on the map, and with further discoveries and experiments — like Thompson’s discovery of the electron and Rutherford’s gold foil experiment — improved models of atomic structure were introduced.

The first GIF above shows Rutherford’s planetary model, which was proposed in 1911. In his model, negatively-charged electrons orbit an incredibly small, dense nucleus of positive charge. Despite being a completely incorrect model, most people still think this is what atoms really look like*. This is not an atom. It’s physically impossible for electrons to stably orbit like this, and the idea of orbiting electrons was entirely replaced by 1926.

I can’t say what an atom actually looks like, but the most accurate model we have today is governed by the laws of quantum mechanics. The location of an electron is determined by a probability distribution, called an atomic orbital, which tells us the probability of an electron existing in any specific region around a nucleus. The second image shows the surface around a hydrogen nucleus on which an excited electron is most likely to exist.

Mathematica code posted here.

*Advertisements and popular science articles incorrectly represent atoms all the time. Even the US Atomic Energy Commission and the International Atomic Energy Agency use the Rutherford model in their logos!

Wanted: Long-Term Thinking about Technology and Education

The rampant spread of technology-mediated learning has set off fits of hype and hand-wringing—yet the U.S.’s traditional centers of higher education have mostly failed to confront the pace of change and the implications for students. There is probably no way anyone can keep up with this transformation: the technology is simply evolving too rapidly. Nevertheless, we keep trying. Will these developments truly serve our goals for advanced education? We need to know urgently.

image via flickr:CC | karola riegler photography

edshelf Weekly - Tools for Creating Content

One of the most exciting abilities that technology can give educators and students is the ability to make stuff. Unlock a world of creativity and engagement with a computer program, interactive canvas, live presentation, bundle of content, or fun game.

  • Kodable - Teach programming in your school with a Kodable School Plan. Last chance to get 30% off using this link! KICKSTARTER CAMPAIGN SUPPORTER!
  • Drawp for Schools - Give your students a flexible virtual canvas for drawings, photos, sounds, and video with this mobile app.
  • Pear Deck - Use a Google Chromebook or Google Drive? This app allows you to create live, interactive presentations online.
  • Bundlr - Clip any kind of web content - like web pages, photos, videos, and tweets - into bundles that can be shared with colleagues.
  • Jeopardy Rocks - Tired of creating your own Jeopardy games from PowerPoint? Use this handy free online website instead.

Want more? Check out these collections of tools created by members like you.

Enjoy these great tools for educators!

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- Mike Lee, Co-founder of edshelf

Playing games, chatting with their friends, and browsing the internet are all likely suspects drawing your students’ attention away from whatever the task at hand happens to be, but just because students have access to technology doesn’t mean you have to transform into device police and forget about teaching. Even if your students would much rather be watching videos on YouTube than learning about the Roman Empire, you still have the upper hand: they want to be using the device. Period.

So how can you leverage that into students who are actually working on what they should be? Here are a few tips


The Clock is Ticking… 21 days / 23 hours / 54 minutes / 33 sec 

Time is moving fast and the Kaplan Techstars Teams are working their hardest to accelerate their businesses. When we feel like the time is almost running out and we have so much todo before we get on stage on Demo Day, it’s so good to get a surprise like this one. Thank you Justin for sharing your relaxing tones with us and for giving us a great start of a day.