[Topgun]

I have to do a dumb project for school. I have to make a model of the bohr view of an atom. thing is I only studied quantum mechanics . now I know that bohr model also has energy levels but I don't know if all the electrons in one energy level that would normally go into different orbitals go into the same orbit.

basically I don't know if the electrons from, say, a p orbital go into the same orbit.

help?

[Herra Tohtori]

Bohr model is an oversimplification if any.

It only works on a hydrogen atom as far as I know, and even then it's inaccurate compared to orbital model of quantum electrodynamics. Helium might be possible to construct as a model using Bohr model, but it gets difficult... and with anything more complex, using orbitals is pretty much the only way to go. I don't think you could have any real success with a hydrogen molecule either...

Basically though, Bohr model just handles the orbit of the electron much like the orbit of planets. The energy of the electron is stored as kinetic energy, and the velocity defines the distance from the proton, and the centripetal force is the electric force. Unlike with planets that have hardly any effect on each other though, this model is obviously very hard to construct with anything but simply proton and electron orbiting it, since additional electrons repel each other, so the question about simulating more complex atoms in Bohr model is pretty moot, and even if given that kind of assignment I would just not do it.

If you just need to make a visual  representation (drawing, 3d-model), you can oversimplify the orbital levels as "orbits" and just throw the electrons onto their slots. If it's a simulation or some kind of analysis, though, just use quantum mechanics... or make a model of hydrogen atom in Bohr model, then show an attempt to model a helium atom with three objects (+2e, -e and -e) reduced to a three-body problem and then show the quantum mechanics model that actually works for it.

[Topgun]

I will just simplify the thing way down then. I will just use a orbit for every level.
thanks.

[Herra Tohtori]

Well, technically you could draw a dedicated orbit for each electron, but since the electrons on the same orbitals have generally the same energy levels, you would need to make the orbits pretty much the same size for each orbital and the model itself wouldn't get any more accurate, so I guess oversimplification is the way to go (as that is what Bohr model is).

Include the problems though for extra credit. Explain why this isn't an accurate representation of reality.

[iamzack]

We learned bohr model like this: Atom is a pecan pie. Electrons is pecans. Delicious, delicious pie.

[Herra Tohtori]

Actually, that's more like the older assumption that matter consists of positively charged substance where negative electrons are stuck (kinda like raisins on dough, or indeed pecan peanuts in pecan pie). Ernest Rutherford disproved this assumption with his experiment with thin gold foil, proving that most of the atoms is empty space, which led to more modern theories of the nature of matter.

[iamzack]

That whole thing was lame. We spend too much time learning things that we now know aren't true

[Ghostavo]

That whole thing was lame. We spend too much time learning things that we now know aren't true

It's so that you can develop a critical mind and learn about the history of whatever science you're studying.

[iamzack]

We could get that in like ten minutes. Here's what we used to think atoms were like: pecan pie.

It's not history, it's chemistry. We don't hang around learning who discovered every element how.

[Herra Tohtori]

Actually, history of science is rather useful to know. At least I personally always learned stuff better as part of a whole instead of separated entities; being able to attach scientific developements and discoveries to historical times by people always made it easier for me to remember stuff.

Then again that applies for me in other subjects as well. Like history. I was always pants at remembering details like years, but I remembered the order of events and general timescale pretty well, which made it very easy to write coherent essays on exams.

Knowing the history of science is important, damn it!

[Ghostavo]

But it's good to learn how they came to discover that theory and what was the flaw of the previous ones.

For example, first you learn the geocentric model. Afterwards, you are pointed it's flaws and how the heliocentric model fits better with reality. Then afterwards (if at all) you learn that even the heliocentric model has it's flaws, etc...

That way you can have a broader view instead of just the latest theory.

You wouldn't like to be taught at early age Relativity and Quantum Mechanics.

[iamzack]

We don't learn the geocentric model. We also don't learn that the world is flat. We might leanr that people used to think that way and how we came to know otherwise, though.

[Rian]

If all we taught were the most current, most accurate, most complete versions of scientific theories, then it would be very difficult to teach anything below graduate level. If the lower, simplified levels of understanding didn't exist, then it would be all but impossible to get into science at all.

We know that Newtonian mechanics is fundamentally inaccurate. Nevertheless, it’s a useful and necessary component of any physics curriculum because it’s a valid approximation in the vast majority of cases, and because it provides a foundation for more advanced studies. The scientists developing these theories didn’t pull them out of the air; they built on the work of previous generations. Moreover, it’s often true that the easiest way to understand a scientific concept is to follow the progression of logic that led to its discovery. We study the earlier model, point out the holes and inconsistencies in it, and then look at how the subsequent models get around those issues.

The Bohr model was an improvement on the understandings that came before it. It did, of course, have some flaws that could not be solved within a classical understanding, (such as the fact that an orbiting electron would radiate away its energy and spiral into the nucleus within a fraction of a second) but it also made possible some approximations that are still useful today. Quantum mechanics is more accurate, but it sacrifices a great deal of simplicity to do so. While it is theoretically possible to solve the wave function for larger atoms with many electrons, or even molecules, it’s unlikely to happen outside supercomputers. For most practical applications, a simpler model or an approximation is the best way to get a useful result.