Clarification of (misleading?) potential energy diagram

In summary, the conversation discusses the Bohr radius of the first electron, with one person questioning its accuracy and another providing a more accurate representation. The use of the wavefunction and energy levels is also mentioned, with the reminder that energy is quantized.
  • #1
etotheipi
I've seen this figure kicking around, and just wanted to check that I'm not going mad. ##r_{0}## is supposed to be the Bohr radius of the first electron.

1583783363572.png

I don't think this is quite right, since at ##r_{0}## the potential energy is about ##-27eV## or something, so I think they've actually drawn the curve of ##E##. I would instead draw something like this (where T has been added for clarity):

1583783459393.png


with the original red line ##E=\frac{U}{2} = -T##. Is this a justified correction? I'm just asking because there are a lot of images on google which seem to conflate ##E## and ##U## on diagrams, and it's causing me to doubt myself a little... thank you!

Also, as a sort of follow up question, some authors when considering e.g. a particle in a box choose to draw the wavefunction at the level of the energy level. Is this a purely pedagogical choice, since evidently all of the information pertaining to the energy is already encoded in the wavelength?
 
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  • #3
Thanks, that is indeed a lot better. I calculated about ##50\text{pm}## for the Bohr radius and that does indeed correspond to about ##-27\text{eV}## on that diagram.
 

1. What is a potential energy diagram?

A potential energy diagram is a graphical representation of the potential energy of a system as a function of its position or configuration. It is commonly used in physics and chemistry to visualize the energy changes that occur during a chemical reaction or physical process.

2. How is potential energy represented in a potential energy diagram?

Potential energy is typically represented on the y-axis of a potential energy diagram, with the x-axis representing the position or configuration of the system. The shape of the curve on the diagram can vary depending on the type of potential energy being depicted.

3. What is the purpose of a potential energy diagram?

The purpose of a potential energy diagram is to show the energy changes that occur during a chemical reaction or physical process. It can also provide information about the stability of different configurations of a system and the energy required to transition between them.

4. How can a potential energy diagram be misleading?

A potential energy diagram can be misleading if it is not labeled properly or if important factors are omitted. For example, if the diagram does not show the activation energy for a reaction, it may appear that the reaction is energetically favorable when in reality it requires a significant amount of energy to occur.

5. How can a potential energy diagram be clarified?

To clarify a potential energy diagram, it is important to include all relevant information such as the activation energy, energy changes, and reaction pathway. It can also be helpful to label the different regions of the diagram and provide a key or legend to explain any symbols or curves used. Additionally, providing a written explanation of the diagram can help to clarify any potential confusion.

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