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Q & A: Bohr’s Planetary Model

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Most recent answer: 10/22/2007
Q:
i need to find a picture of Bohr’s planetary model of the atom. where would i find this?
- Rose (age 15)
A:
Rose -

Bohr's planetary model of the atom had all of the protons and neutrons clustered together in a nucleus at the center of the atom (like most scientists still believe that they are). Then it had the electrons moving around the nucleus in eliptical (oval-shaped) paths, or 'orbits'. The reason that it's called a 'planetary model' is that the electrons move around the nucleus much like the planets move around the sun (except that the planets are held near the sun by gravity, whereas the electrons are held near the nucleus by something called a Coulomb force). The model atom basically looked like this:



The reason that Bohr came up with this model had to do with the ways that different atoms can absorb or emit certain colors of light. It did a decent job of predicting these colors for the hydrogen atom, although with some errors. It was nearly useless for other atoms, and failed to capture most properties of atoms and molecules at all. A model is one where the electrons move around the nucleus in something more like a cloud. For a picture of this, and another picture of a Bohr planetary model atom, check out the answer to the question .

-Tamara

(published on 10/22/2007)

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