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Q & A: The Bohr Model

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Most recent answer: 11/05/2010
i need a picture of the bohr model. can you please help me?! thank you
- Jillian Bernardo (age 14)
erin moar middle school, jefferson city utah
Jillian -

The Bohr Model of the atom depicted the atom’s nucleus as a lump of protons and neutrons with the electrons circling it in neat, tidy orbitals.

In modern models  the electrons are spread out around the nucleus in ’clouds.’

(published on 10/22/2007)

Follow-Up #1: atom energy

We're learning about the theories of models of atoms, and in Bohr's model the book says "the energy must be given out when 'excited' electrons fall from a high energy level to a low one". What does that mean? I can't understand it and I have a test in a few days..........plz help
- Anonymous
The meaning is perhaps even simpler than it might sound. At the start here the atom is in a state that has a certain amount of energy. It ends up in a state with less energy. The total amount of energy never changes. So the missing energy went somewhere else. Typically it leaves as a little blip of light.

Bohr doesn't really have much to do with it, except in one regard. In the Bohr model, as in real quantum mechanics, the possible energy values for the atom aren't spread out continuously, but form a set of unevenly spaced steps. In the Bohr model atoms are always supposed to be in states with only one of those definite energy values, but actually mixed states also occur.

Mike W.

(published on 11/05/2010)

Follow-up on this answer.