How could that be if the plumb pudding model was correct? Rutherford's experiment prompted a change in the atomic model. If the positive alpha particles mostly passed through the foil, but some bounced back. AND if they already knew that the electron was small and negative, then the atom must have a small positive nucleus with the electrons around them.
The model proposed by Niels Bohr is the one that you will see in a lot of introductory science texts. There are a lot of good ideas in this model, but it is not the one that agrees with all of the current evidence. The model tries to make a connection between light and atoms.
Suppose you take some light and you let different colors bend different amounts think rainbow. This way, you could see what colors are present for different light sources. Here are three different light sources. Maybe the light from the light bulb is what you would expect. These are the colors of the rainbow. However, suppose you took some hydrogen gas and excited it. There would only be certain colors only certain wavelengths of light produced. If you shine light through some hydrogen gas, there will be dark bands of light at those same colors.
So, Bohr said that these colors of light in the hydrogen gas correspond to different energy levels the electron in hydrogen can have. This is crazy at least it was crazy for its time. Think about a planet orbiting the Sun. It can be at any energy level. In this case, there is a gravitational force attracting the planet which produces orbital motion. This will work anywhere in the solar system.
Early physicist thought of the electron in an atom a lot like a planet orbiting the Sun. The key difference is that the electron in the Bohr model orbits due to an electric interaction and not a gravitational interaction. Well, the other difference in the Bohr model is that the electron can not orbit if it does orbit, which it doesn't at any distance and any energy. Here is the essence of the Bohr model. The Bohr model depends on a connection between the frequency of light and the energy of the level change.
If light of a frequency corresponding to the energy change interacts with the atom, the electron can absorb the light and jump up a level. If an excited electron jumps down a level, it looses energy.
The energy the electron loses becomes light with a frequency corresponding to a the change in energy. The Bohr model can be quite confusing to introductory students, but the important point is that this model agrees with the following evidence.
There is a key point about the Bohr model that is no longer accepted in current models of the atom. In the Bohr model, the electrons are still thought to orbit the nucleus just like planets orbit the sun.
Aug 16, Aritra G. Jun 6, Defects of the Bohr's model are as follows - 1 According the the uncertainty principle, the exact position and momentum of an electron is indeterminate and hence the concept of definite paths as given by Bohr's model is out if question. Related questions How can the Bohr model be used to make existing elements better known to scientists? How did Niels Bohr change the model of the atom?
Question fc19d. Question e In atomic physics, the Bohr model depicts an atom as a small, positively charged nucleus surrounded by electrons. These electrons travel in circular orbits around the nucleus—similar in structure to the solar system, except electrostatic forces rather than gravity provide attraction. The Bohr model was an improvement on the earlier cubic model , the plum-pudding model , the Saturnian model , and the Rutherford model Since the Bohr model is a quantum-physics-based modification of the Rutherford model, many sources combine the two: the Rutherford—Bohr model.
While the Rydberg formula had been known experimentally, it did not gain a theoretical underpinning until the Bohr model was introduced.
Not only did the Bohr model explain the reason for the structure of the Rydberg formula, it also provided a justification for its empirical results in terms of fundamental physical constants.
Although revolutionary at the time, the Bohr model is a relatively primitive model of the hydrogen atom compared to the valence shell atom. As an initial hypothesis, it was derived as a first-order approximation to describe the hydrogen atom. Due to its simplicity and correct results for selected systems, the Bohr model is still commonly taught to introduce students to quantum mechanics.
A related model, proposed by Arthur Erich Haas in , was rejected. Early planetary models of the atom suffered from a flaw: they had electrons spinning in orbit around a nucleus—a charged particle in an electric field.
There was no accounting for the fact that the electron would spiral into the nucleus.
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