Faynman talks about atoms repelling and attracting each other

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Discussion Overview

The discussion revolves around the concepts of atomic interactions, specifically focusing on the forces of attraction and repulsion between atoms as described by Feynman. It explores the conditions under which these forces operate, the role of kinetic energy, and the implications for chemical reactions. The scope includes theoretical explanations and analogies related to chemistry and physics.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant references Feynman's explanation that carbon can repel or attract oxygen depending on distance and kinetic energy, questioning whether the forces involved are the same.
  • Another participant describes the balance of attractive and repulsive forces between atomic charges, explaining that energy must be introduced to overcome repulsion for atoms to bond.
  • There is mention of exothermic and endothermic reactions, detailing how energy changes affect molecular stability and thermal energy release or absorption.
  • A participant seeks clarification on the meaning of negative potential energy in the context of atomic interactions.
  • Another participant provides an analogy involving an RJ-45 connector to illustrate the concept of resistance and force in atomic interactions.
  • Further clarification is sought on the analogy of potential energy, with a distinction made between attractive and repulsive systems.
  • One participant acknowledges the use of analogies in understanding complex concepts, suggesting that models are inherently simplified representations.

Areas of Agreement / Disagreement

Participants express varying levels of understanding and seek clarification on specific points, indicating that there is no consensus on the interpretation of potential energy or the implications of the analogies used. Multiple competing views and interpretations remain present throughout the discussion.

Contextual Notes

Limitations include the potential for misunderstanding the analogies used, the complexity of atomic interactions, and the varying interpretations of energy changes in chemical reactions. The discussion does not resolve these complexities.

Who May Find This Useful

This discussion may be of interest to individuals studying chemistry or physics, particularly those looking to understand atomic interactions and the principles of energy in chemical reactions.

johann1301
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In this vid, Faynmen explains what a fire really is:

just watch from start till 1:22


He says that sometimes carbon repels air(O2) and sometimes they attract each other. If they attract, they start a fire. Whether they do repel or not is dependent by the distance between them or their kinetic energy. His analogy is a ball rolling up the side of a volcano, if the ball isn't pushed hard enough the ball goes back again. If its pushed hard enough the ball falls into the hole of the volcano.

Is the force repelling and the force attracting the same force? (electromagnetic??) If so how does this work? What makes this one force do two opposite things?

I know this might belong in the chemistry section...
 
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Each atom has a positive charge (protons) at its middle and a negative charge (electrons) on its outside. Individual molecules and solids are held together by the fact that the net energy of attraction between the positive and negative charges is greater than the energy of repulsion. The total Potential is said to be negative.
When two atoms come close together, the negative charges of each are nearer to each other than they are to the other atom's positive charge. If they are just 'sitting there' the repulsion between each atom's electrons will keep them apart. To move them closer together would require some energy to be introduced (as in squashing a spring).
If they come together fast enough (with enough Kinetic Energy - often called Activation Energy)) AND if the resulting molecule would happen to be stable, then the energy is sufficient to overcome the (positive) energy of repulsion and the electrons then come under the influence of the positive nucleus and are attracted. The electrical potential energy is then negative and you have a molecule. The equivalent to pushing a boulder up and over the lip of a deep volcano.
In the case of an Exothermic Reaction, the resulting drop in the energy of the combination has to go somewhere and manifests itself as thermal energy because more energy comes out than you put in as KE.
In the case of an Endothermic Reaction, the atoms still stay stuck together but the KE that you put in is greater than the overall change in Potential energy so thermal Energy is actually lost from the surroundings. (It takes heat out)
In Thermal Decomposition, if you supply enough Kinetic energy (collisions from nearby fast molecules) the molecule can be knocked apart into its constituent atoms.

It, of course, gets more complicated but that is the basics of it. Interestingly, there is a similar set of circumstances which determine when atomic nuclei come together with a bang, whether they will bounce off or fuse together.
 
Thank you;) I am reading now, trying to understand everything you said. Perhaps Ill ask another question about it later when i know what to ask.
 
The total Potential is said to be negative.

What does this mean?
 
johann1301 said:
Thank you;) I am reading now, trying to understand everything you said. Perhaps Ill ask another question about it later when i know what to ask.

You know the Internet cable that plugs into the back of your computer? It's called an RJ-45 connector.

When you plug it in, it resists a little because the plastic spring tab needs to be pushed down as you push the connector in.

Once you've pushed it in far enough the plastic spring clicks into place and now it would take even more force to pull them apart again.
 
johann1301 said:
What does this mean?

Negative potential means you get energy out as you get closer (i.e. like rolling down into a valley). Positive Potential needs energy put into get closer - (like needing to be pushed up towards a peak).
All Attractive systems (Earth's gravity etc) have negative potential. Repulsive systems (Two similar charges) have positive Potential. It has to be that way round to account for things gaining Kinetic Energy as they fall towards Earth (as height gets less).
 
Once you've pushed it in far enough the plastic spring clicks into place and now it would take even more force to pull them apart again.
Im assuming this is an analogy, or isn't it? Confused becouse i know there is an electromagnetic force holding the plastic together..
 
Of course it's an analogy. Every model you will ever hold in your head will be an analogy. If you can accept that than you may feel less bad when you don't feel you've understood something.
 

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