This item is in two parts. The first part is a text based discussion of the Bohr model of hydrogen. Included is a link to a mathematical appendix that contains the basis for a derivation of energy levels and radii.

The second part of the item is a "simulation" of the Bohr model of the hydrogen atom. The simulation can display either particle or wave aspects of the Bohr atom. In the particle mode one sees the various orbits at the relative radii for the chosen principle quantum numbers. In the wave mode you see the deBroglie standing wave superposed on the circular orbit trajectory. The user may choose which principle quantum number to display. In wave mode the user may shift the orbital radius and see that the deBroglie wave only forms a standing wave at the appropriate radii corresponding to the principle quantum numbers.

The energy and the classical radius of the orbit are automatically calculated as you change principle quantum numbers. A typical energy level diagram is displayed with the energy of level of the current quantum number choice highlighted.

Overall, much of the information presented is a text page with the addition of a simple animation. The text discusses background and assumptions used to develop the Bohr model. The concepts displayed by using the animation can help users understand how this model was developed.

Type of Material:

This is tutorial with interactive simulation material. The web page item contains text and a Java Applet simulation.

Recommended Uses:

The material would best be used as review for features of the Bohr model. The simulation can be used to illustrate how the deBroglie wave hypothesis relates to the quantization of angular momentum and standing waves. This may be used to support lectures as a demonstration, or for homework with a carefully guided assignment.

Technical Requirements:

Java

Identify Major Learning Goals:

The major learning goals are for the student to familiarize themselves with the quantization of energy levels in the Bohr atom. Students will be able to observe how the model incorporates a standing wave requirement,
and can then relate this to a quantization of angular momentum (via deBroglie hypothesis). Students will also be able to examine how the radii and energy levels change with changes in the principal quantum number.

Target Student Population:

This material would serve for very advanced and capable high school students and students in any of the large variety of introductory physics or astronomy courses that study the Bohr atom.

Prerequisite Knowledge or Skills:

Some knowledge of uniform circular motion and some background regarding wave description of particles will be helpful for fully appreciating the applet.

Content Quality

Rating:

Strengths:

The item gives a good historical discussion and brief derivation of energy levels and radii. The simulation is simple but allows users to easily investigate aspects of the Bohr model. The physics is correct and appropriate to a variety of introductory level users. The author quite appropriately warns the user of limitations of the Bohr model of the atom.

Concerns:

The material is very limited in scope. Activities will need to be developed.

The numbers displayed for energy and radii need to be examined carefully to determine relevant trends.

Potential Effectiveness as a Teaching Tool

Rating:

Strengths:

The outstanding feature of the applet is the ability for the user to look at the different radii of orbits and see if the deBroglie wave forms a standing wave or not (closes in on itself). This point is often hard to visualize with the typical textbook diagram and this applet serves to show this constraint in a useful visual manner.

The mathematical link provides a nice and well laid out description of the mathematical elements in deriving the necessary results for the Bohr model. This would provide a nice review for students.

Users may also examine changes in either the energy levels and in the Bohr radii as they change the principal quantum number.

Concerns:

The applet is limited in its usefullness, stemming from minimal interactivity available to the student.

Ease of Use for Both Students and Faculty

Rating:

Strengths:

The controls are well laid out, are intuitive and easy to use. The discussion is kept at an introductory level. Even the mathematical appendix can be followed by students without advanced physics. Users will need to read the instructions to see what can be done with respect to interaction and the wave model.

Concerns:

The item has very limited interactions. The numbers for the radius and energy level disappear when the wave model orbit is pulled in or out from a stationary state (Bohr model) orbit. It can be difficulty to find the exact position to make numbers reappear again. One must be "dead on" at a new orbit.

The placement of the derivation in an "appendix" link suggests a low priority for looking at that material.

Creative Commons:

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