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My 8th grade student asks me: "Why don't electrons just fall into the nucleus?" I don't want to lie and tell them it's "just like the Moon not falling onto Earth, because of, you know, acceleration". I also don't have time to elaborate on quantum mechanics. What should I tell them?!

Pifagor
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    I am of the opinion that these questions belong on [parenting.se] rather than [physics.se], because chose the language to use for an eight year old is not really in keeping with our stated mission "a question and answer site for active researchers, academics and students of physics and astronomy". – dmckee --- ex-moderator kitten Oct 24 '15 at 22:52
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    That said, we've already answered the physics question in detail more than once: http://physics.stackexchange.com/questions/9415/why-do-electrons-occupy-the-space-around-nuclei-and-not-collide-with-them http://physics.stackexchange.com/questions/20003/why-dont-electrons-crash-into-the-nuclei-they-orbit? and many other to be found in their sidebars. – dmckee --- ex-moderator kitten Oct 24 '15 at 22:53
  • 8th GRADE, not 8 year old. – Pifagor Oct 24 '15 at 22:53
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    Hm. Sorry. Then I am much more tempted to call the above links duplicates. They include answers at a number of levels of sophistication. Perhaps there is one there that fits your needs. – dmckee --- ex-moderator kitten Oct 24 '15 at 22:56
  • Even at 8 years old, I find that children are ready for the statement that the electron is not like the Moon. When we look at things as small as an atom, we can't think of the electron as a little ball and instead it is a thing that is spread over a nonzero region of space. Naturally, this will leave them a little mystified, but eight year olds will go off and research the topic on Wikipedia. I would suggest making this statement, and then inviting the children to explore the www. You'd direct eight year olds to Wikipedia, and eighth graders to the questions that dmckee marked. – Selene Routley Oct 24 '15 at 23:41

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Tell them about QM!! I mean, don't spill the gory details, but let them know that (something like) this was a major question in early 20th century physics, and that to answer that question requires a more sophisticated description of the atom. Also, they probably all have computers. Email them a link to this: https://en.m.wikipedia.org/wiki/Introduction_to_quantum_mechanics

They don't need to understand everything, but I think its a pretty important lesson that physical theories all have varying levels of accuracy and corresponding complexity. The sooner they have this perspective the better!

anon01
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  • Absolutely. Even at 8 years old, I find that children are ready for the statement that the electron is not like the Moon. When we look at things as small as an atom, we can't think of the electron as a little ball and instead it is a thing that is spread over a nonzero region of space. Naturally, this will leave them a little mystified, but eight year olds will go off and research the topic on Wikipedia. I would suggest making this statement, and then inviting the children to explore the www. You'd direct eight year olds to Wikipedia, and eighth graders to the questions that dmckee marked. – Selene Routley Oct 24 '15 at 23:42
  • haha! Those had better be some damn smart eight year olds to get through that wikipedia page... I think tetris was more my speed at that age :) – anon01 Oct 26 '15 at 02:38
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    My daughter is in grade 3 and most of her peers are eight years old. I'm astounded how much the interested ones can pick up. Anything algebraic is beyond most of them, but what meaning they can glean from well written text is amazing. – Selene Routley Oct 26 '15 at 03:09