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Name: Daniel
Status: student
Grade: 9-12
Country: USA
Date: Winter 2012-2013


Question:
In Bohr's model of electron orbits, he clearly defines that when an electron "jumps" from one energy level to another when the atom is making a transition between states, the electron cannot exist between the energy levels and can only exist on one level or another. One of my teachers told me that he thinks the electron travels through a higher dimension to get to another energy level. Does this idea in any way agree with current theories or models of electrons or electron orbits?

Replies:
Current theories do not really try to explain or more deeply understand the Bohr model. It is a useful model because it provides an intuitive explanation of energy quantization, and that's probably a good place to leave it, because it doesn't get important details right. We're free to imagine anything we like about how electrons change from one energy level to another, but the most valuable mental pictures are those that explain something measurable or suggest testable hypotheses.

Tim Mooney


First, remember the Bohr model is an approximation, ignoring a lot of the finer points of the hydrogen atom. For example, the H nucleus is not a point, it has a small, but finite volume. The Bohr model neglects this. Second, the Schrödinger equation, a better model of the electron, describes the electron as a wave, not a point. So the position of the electron is a “probability” not a point in space. Both the Bohr model and the simple format of the Schrödinger model ignore the fact that both the spin of the proton and the electron exist, and they interact. That does not mean that the electron does not exist at all “between” orbitals, but rather, the probability of finding the electron in that space is finite (but small).

Invoking a “higher dimension” is not well defined. You have to answer the questions: Where did that dimension appear from? What are the properties of this proposed “higher dimension”? There are also other problems, but you get the idea I think.

The problem is this. As you add “corrections” to help explain the behavior of an electron “between” states, the mathematics quickly gets exponentially more complicated, and consequently and the nice simple picture becomes more and more obscure. The following web site illustrates this increase in abstraction:

http://www4.ncsu.edu/unity/lockers/users/f/felder/public/kenny/papers/psi.html

It is not that the problem of what happens to an electron during the process of transition has not been studied, so much as, the physical interpretation becomes more and more obscure in the mathematics.

Vince Calder


No.

A better answer is that the electron takes an orbital configuration that has higher energy. This does not involve any 'higher dimension', but it does involve the particle-wave duality proposed in quantum theory. To understand this statement, I suggest you read about atomic orbital theory, there are plenty of online resources.

The 'higher dimension' idea suggested by your teacher may be based on the common misconception that electrons are solid objects with defined quasi-newtonian orbits (like mini planets). This is not the case. When we say an electron 'jumps', it is not a physical description if how it moves. It is simply a colloquial choice of words, perhaps influenced by stack-style electron energy diagrams.

Hope this helps, Burr Zimmerman


Hi Daniel,

I applaud that your instructor was laying foundation for teaching the relatively advanced Quantum Model by first teaching the Bohr Model. The Bohr Model was a profound step in understanding the atom and lead to the development of the current model. The Bohr Model is still useful for certain explanations of atomic behavior.

An electron is not analogous to a Moon orbiting a planet. Orbital electrons are wave functions that occupy limited positions and states within the shells of an atom. Heisenberg's Uncertainty defines that either position or motion may be measured, but not both. So in the orbital, there is a probability of detecting the electron in a certain place. This probability means electrons appear and disappear among locations in the orbital. Electrons tunnel, they jump from one atom to another without crossing the space. Electrons exhibit quantum mechanical behavior with discreet energy levels, emission and absorption of light that is time independent and yet the electromagnetic wave has a time characteristic(m/s). The electron exists in and manipulates X,Y,Z, Time and Space-Time continuum; therefore they would certainly invoke dimensional transitions.

Hoping this helps. Peter E. Hughes, Ph.D. Milford, NH


Daniel, An electron in an atom is not a particle at one point in space. The electron is in an energy state that includes many positions at one time. A particle as we see it with our eyes, like a particle of dust, does not correspond to what quantum physics calls a particle. A particle has a ?probability distribution? of position, momentum, energy, and such. Some quantities have completely unknown values. Some can have specific values. Some may have several specific possibilities. Which quantities are specific and which have no exact value depends on what has been measured, as well as what the particle is doing.

In an orbit within an atom, an electron?s energy and angular momentum have specific values. Position is defined by a ?cloud? around the atom?s nucleus. The electron is throughout this cloud. If the electron jumps to another energy level, the shape and size of the corresponding cloud changes immediately. There is no single particle moving through space from one radius to another.

When we measure how an object made of billions of protons, neutrons and electrons moves, the position of each particle is uncertain. Each particle has a range, a cloud of positions. Each particle can be in many places at once. The object, perhaps a baseball, has a baseball that is an ?average? position. You can know exactly where a baseball is, but you cannot know exactly where any one of its particles is. Nobody completely understands it. Our languages do not have words to describe some of the properties, so scientists must either invent new ways to use the words we already know or create words that nobody has ever used. This is what can make subjects such as quantum physics extremely fascinating.

Dr. Ken Mellendorf Physics Instructor Illinois Central College


Hi Daniel,

Thanks for the question. You are correct in that an electron cannot exist between energy levels. Let me make that statement more precise: The electron cannot be found between energy levels. When an electron transitions from one energy level to the other energy level, the electron enters what is called a superposition which is the sum of the two electron energy levels. The electron then collapses (or falls) into the other energy level. This statement comes from quantum mechanical theory.

This superposition may be what your teacher is referring to as a "higher dimension". I want you to know that the dimensions that your teacher is referring to are mathematical dimensions and not physical dimensions.

I hope this helps. Please let me know if you have more questions. Thanks Jeff Grell


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