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Layman understanding Atom movement with added energy

  1. Feb 5, 2014 #1
    Hello there,

    I've for a long time thought that movement energy is transferred through collisions, one atom hits another and transfers it's momentum (Billiard balls). When they're stuck in a rigid structure like a metal, they vibrate until the energy of vibration exceeds the energy of their bonds..or something like that.

    I've also had a hard time separating movement energy, from light energy packets; I have thought during collisions energy is transferred to those electrons which then somehow transfers it to the nucleus to give it momentum. This can start to become confusing than if you add the exact amount of energy needed to move an electron to the next orbital; I guess than it does not gain any speed and the electron eventually lets go of the energy eventually returning it to the same state. Because it seems that any piece of matter can adopt any speed, I feel that I am missing something important, or even making some very incorrect assumptions about how these things work.

    Lets create a few scenarios that might help explain my understanding of things:
    -Atom slowly increases speed eventually having a movement energy which is the same as the energy needed to bump up the electron to the next level (I would think the speed would increase as normal and the electron would stay where it is)

    -Atom is hit by another atom which instantly transfers the exact energy needed to bump the electron up to another higher orbit (I would think the atom would stay still, yet the electron would jump to the next orbit)

    -Atom is hit by another atom which transfers a surplus of energy to bump up the electron to the next orbital (electron jumps to next orbital, excess energy is converted into movement energy).

    This does not help me to explain reflection very well; in fact I thought that any wavelength of light energy added to an atom would be reflected unless it's energy was equal to or exceeded the next orbital energy; this of course is a wonderful contradiction.

    I'm not very proficient in the mathematical language, I prefer the nice visualizations that could be explained to a child (I have a hard time with analogies though). I am working on the mathematics slowly, but at the moment I cannot translate mathematics into a visual model unless it is very simple (many of the symbols are still very foreign to me as well, so a simple equation can appear pretty complicated to me if I don't understand the mathematical operation the symbols represent).

    Many thanks for any help you can provide
     
  2. jcsd
  3. Feb 5, 2014 #2

    Simon Bridge

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    You have the standard, basic laymans level, pictures.
    You have probably noticed that they don't work for all situations you can imagine.
    This is not surprising - because they are layman pictures.
    To go further, you really need the non-layman pictures. There is no other way.

    I can see what I can do - but you should realize that you should get the real physics here.

    The electron excitations are relative to the nucleus.
    Consider - is the entire atom is accelerating, then the electrons accelerate at the same rate as the nuceus ... so their movement relative to the nucleus remains the same.

    I think you need to distinguish between the motion of an atom - it's kinetic energy - from the excitation energy of an atom that comes from electron getting "bumped up to the next level".
    One way of picturing it is that the kinetic energy is the whole atom moving about while the excitation energy is a vibration of the atom. Thus, an atom moves from place to place and vibrates at the same time. Speeding it up does not affect the vibration.

    The details depend on the exact nature of the "collision" - we would say "interaction".
    The two atoms may just bounce off each other like billiard balls, they may form an atomic bond, or one may grab an electron or two off the other and otherwise leave each other alone ... or some combination of them.

    Being composite object, collisions can be quite complicated. However, collisions between atoms need not result in an excited atom.

    Yep - there are a couple of ways of looking at refection of light from a solid.

    1. the electromagnetic fields binding the solid alter the speed of light in the volume of the solid - this results in some light bouncing off and some refracting. i.e. it's a result of light interacting with the space or with the electromagnetic field in that space.

    2. light is absorbed and re-emmitted in interactions with electrons ... when the energy of the incoming photon matches an energy gap for the electron, the electron can hang on to the photon for a while before re-emmitting it ... this is absorbtion. If the photon energy does not match, then the photon is released almost right away... in a random direction.
    The laws of reflection and refraction are emergent results ... you have just entered the world of Quantum mechanics: in that world, particles only follow the rules on average, the details are statistical.

    The exact form the reflection takes depends on details of the surface as well as the light.

    Don't we all!!
    The concepts you are dealing with are not able to be described by nice visualizations.
    If all this physics could be explained to a child with little math, then we wouldn't need to go to college to learn this stuff.
     
    Last edited: Feb 5, 2014
  4. Feb 5, 2014 #3
    Hey thanks for replying, I did type up a long reply asking more questions, but found myself bombarded by new questions and a little tired so gave up on it. You have explained things pretty well although I have probably more questions than before. The vibration and kinetic movement being different is a big revelation to me as well as energy being absorbed regardless of whether it kicks an electron up to the next valid orbit or not.

    I think I can understand why simple explanations will not do; if you do not understand correctly in the first place a lot of questions that proceed that understanding could be based on a flawed understanding and hence be incorrect. This is of course me!

    I was initially put off mathematics as I cannot do rote memorization at all, I need to understand how certain mathematical principles function to really remember them. Recently I have tried learning some new ideas and have had some success, or at least my understanding of things I did not really understand before has been expanded. I kind of figured (perhaps incorrectly) that mathematics would be used to create a precise working model for something that could be visualized, although I have heard it many times before that not all can be visualized. I hear quantum mechanics is a bit like that.

    In any case you have given me a few replies that have changed my fundamental understanding of atoms, so I think it is time to do some research of my own.

    Thankyou for taking the time to explain things to me in such a basic way.
     
  5. Feb 6, 2014 #4

    Simon Bridge

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    This is normal.

    Kinda - think of something you know a lot about - a core skill required for a job you've done long enough to get good at it or something like that. Now imagine trying to explain that skill to someone who has no previous idea about the job, has never done it, and you are not allowed to use any of the terms you learned on the job.

    Me neither ;)
    There are other ways to learn stuff.

    Physics uses math as a precise way to describe ideas - working the math tells us the relationships between the ideas so that we can check them against reality. Math is a language.
     
  6. Feb 6, 2014 #5
    If you have a deep enough understanding of any topic, I think explaining it to the layman does become easier. The trick is explaining it in such a way as to communicate with the fewest errors possible (or without the reciever misunderstanding); that is an invaluable skill. Thanks once again for attempting it.

    I've heared this being said before; it certainly uses lots of interesting squiggles and symbols. It is satisfying though when you can recognize a couple of them. I find with my proficiency as it is, I am often correcting my mathematics to reflect reality :)
     
  7. Feb 6, 2014 #6

    sophiecentaur

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    There is much less 'rote' learning when learning Maths than many people tend to think. There are many jobs that involve learning learning learning every day (stores clerks, shopkeepers ) yet the people who do those jobs very well would say they couldn't 'remember all that Maths'. Likewise, people learn the words of totally nonsense songs after hearing them only a few times. Maths involves more repetition and practice than 'learning' and it also gets very hard (there's always a 'too hard' level for everyone) yet the complaint is always about the quantity of learning. Look at the very few pages on GSCE revision sheets, for example; far fewer words and 'phrases' than there are Premiership Footballers' names and the history of match scores. Brute memory is very seldom the limitation.

    You say you have had some recent success with this stuff. That is probably because your motivation has kept you at it for long enough for you get results. This is a huge advantage of getting older - you accept deferred gratification and give things a bit more time. Whatever they say about the brain going downhill after the early twenties, we can all make better use of what's left on the long trip to senility.

    Also, you don't need to 'know' all the Maths you read on these pages - get used to the general forms and patterns and have faith that 'someone' could explain it to you if necessary. We don't know what's in all the black boxes we use every day - we just use them.
     
  8. Feb 10, 2014 #7

    Simon Bridge

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    I think you need to try it.
    You'll discover that it is a layered process, if you want to minimize error. You start out by introducing the layman, gradually, to the technical language and jargon for the subject along with the peripheral concepts and, as they gain proficiency, you start on the more technical aspects.

    You'll probably get a lot of insights just from reading answers to other people's questions in these forums. At the bottom of this page is a list of related threads for example - compare how those got answered to this one ;)

    This is the same with any language ... just look at all the squiggles and symbols that go to make up this sentence!

    This is normal - maths can be used to describe things that do not exist - just like any useful language.
     
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