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The Space Between Atoms -- Teaching Middle School

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  1. Oct 24, 2014 #1
    Hi guys,

    I know that if we consider a basic atomic model ( not considering quantum mechanics here) that an atom is mostly empty space ( 99.99999%) or something like that.

    But how about the space between the atoms? Would it be appropriate to tell middle school students...8th graders... that there is more space between atoms than the space the atoms take up themselves ( in typical solids, liquids, and gases)?

    Again, I want to reiterate I am introducing them to a crude marble model and speaking of only water "particles" or gold "particles", but they don't understand that "nothing" exist in the spaces between these atoms i.e they think it is filled with air.

    Again, can I say that there is more space between these atoms than the space the atoms takes up themselves?

    I want to reiterate these are eight graders who believe air fills the gaps between gold atoms, for example.
     
  2. jcsd
  3. Oct 24, 2014 #2

    jedishrfu

    Staff: Mentor

    You could do this computation yourself and show them how you came to the conclusion. Find a source that tells you the diameter of the atom and then compute its volume. The periodic table will give you its weight.

    From there you measure the physical objects weight and volume showing the remaining space.

    Or conceptually use a box of BBs in a bigger box and ask them to compute how many objects are inside based on weight and volume of the box.

    I think the notion of space inside an atom vs the space between atoms will have little meaning to them.

    This article says it can vary from a few nanometers to a meter or more

    http://en.m.wikipedia.org/wiki/Atomic_spacing

    Perhaps you could use some balloons, drop a BB in each balloon and tell them that's the nucleus. You blow the balloons up and give one to each kid and have them stand far apart and explain the notion of solids vs liquids vs gases by changing the spacing and for solids lining them up in a grid formation or bowling ball formation...
     
    Last edited: Oct 24, 2014
  4. Oct 24, 2014 #3
    At this point I am not teaching them about the structure of the atom itself. I am more concerned with helping them understand that there is space between particles, and that this space is actually considerably large compared to the particle itself ( or is it? This is what I am trying to figure out.)

    Also, since I am only using the term particle at this point, the "marble" that represents the particle includes the additional radius added by the electron orbiting the nucleus.
     
  5. Oct 24, 2014 #4

    mfb

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    2016 Award

    Staff: Mentor

    Only for gases, and only if the pressure is not too high.

    In solids and liquids, the atoms are packed close together - about the same density you get if you throw balls in a bucket until it is full.
    Atoms are not billard balls and don't have a fixed radius so this is not a perfect model, but it is not so far away from the right density.

    Now you can compare typical densities of solids to the density of air to find out how much empty space there is in the air (the atoms are not the same unless you have access to liquid air, but to get an idea you can neglect this difference).
     
  6. Oct 24, 2014 #5
    Okay. Thank You. l am doing a discrepant event where they mix 5mL of isopropyl alcohol with 5 mL of water and have them observe a total volume of less than 10mL!

    Before this discrepant event, I was going to have a teacher "fact" on the board, and have them ask questions about it. My fact was going to be something about how their is empty space between particles.

    Maybe I can say something like "particles in a solid have empty space between them, in a liquid even more empty space, and in a gas like air in the room even more space than the particles themselves".

    The alternative is to give them a "fact" which is actually not true at all...like

    " Particles is a solid, liquid, and gas can';t have empty space between them. There must be SOMETHING that fills the gaps." (This is what they actually think). Then have them do the discrepant event and address whether the teacher "fact" is true or not.
     
  7. Oct 24, 2014 #6

    jedishrfu

    Staff: Mentor

    You could also do the rocks pebbles sand and water demo afterwards...

    and of course the reverse demo...



    for a different kind of take on things.
     
  8. Oct 24, 2014 #7

    DaveC426913

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    Gold Member

    What if you showed them a bingo machine?
    atom-action-blower.gif
    It would illustrate how atoms fill a space simply by bouncing off each other.

    Unfortunately, what it would not do is disabuse them of the notion that the space between atoms is full of air.
     
  9. Oct 24, 2014 #8
    The simplest model would be to talk about crystalline metals. Two of the most common crystal structures (FCC and BCC) have 74% and 68% of the space filled with atoms and the rest is free space (the space between the atoms). This model assumes that all atoms are spheres of equal size. Actually the most densely that you can pack spheres of equal size is 74%. This would be a very easy activity to show 8th graders. Wikipedia has a good article on this, and I like how they give some historical perspective on the packing of cannonballs (http://en.wikipedia.org/wiki/Close-packing_of_equal_spheres).
     
  10. Oct 25, 2014 #9
    Laura thank you so much! I am definitely going to use this curing my explanation.

    Also jedishrfu, I was going to do something similar during my explain portion( after the exploring with the discrepant event).
     
  11. Oct 25, 2014 #10
    They are not completely wrong. See this video (particularly at 3:20):



    Some of the particles will always be hurling through the voids like "air" particles hurling through the empty space around you.
     
  12. Oct 26, 2014 #11
    Godparticle -
    That is beside the point. Again, this is for eight graders. If you wanted to get very technical we would be talking about quantum wave functions and probability distributions, but that isn't really the point here.

    One more question though, how can I convince them that air isn't between the particles in a solid.

    What activity could I do with them that would challenge this notion?

    I like packing of spheres. Maybe I could have them put marbles in a small beaker and have them answer questions about how this is a proper model and how it isn't?

    But then again,the empty space would be filled with air :/ ....with their model.
     
  13. Oct 26, 2014 #12

    jedishrfu

    Staff: Mentor

    You can show them the feather dropping in a vacuum vs the feather dropping in air explaining the reason this is so. Then ask them to draw a box with a pencil and sprinkle some dots inside. Tell them if they could use a really powerful microscope this is what they would see and have them draw a feather there with the air particles bouncing off of it slowing its descent.

    Einsteins paper on the explanation Brownian motion was the first clear evidence for the existence of atoms even though they had been theorized for years. Feather dropping is another piece of the puzzle.
     
  14. Oct 26, 2014 #13
    Thanks for the ideas guys. I think what I am going to do is have them write a poem and reflect on the concept of nothing or empty space. This will help them reflect on what it means when I keep explaining to them that their is empty space between particles. Also I do not have much time at the end of my lesson ( only a 5o minute class or so) to do another activity besides the lab.
     
  15. Oct 27, 2014 #14
    Please let us know how the lesson turned out. I find this very interesting. The idea that there is "nothing" between the atoms can become kind of disturbing if you think about it for awhile. How many of the students really "get it?"
     
  16. Oct 27, 2014 #15
    Okay I will definitely keep you guys updated. This lesson plan is actually part of my graduate program for my master's program. It is a prior knowledge lesson plan i am doing. (I am only a student teacher). I had students take pre-tests and interviewed individual students to get a better idea of what they were thinking. Even the high acheiving students seem to think air fills the gaps. Plenty of research shows that the students have a difficult time grasping the concept of empty space, and consistently prefer a continuous model of matter.

    I am doing the lesson this Thursday, and probably the post-assessment Tuesday next week.
     
  17. Oct 29, 2014 #16
    Hello
    The problem with considering empty space to be air is just the limitations of our senses providing us with our intuitive frame of reference. It seem to me the only way to get children to "step out of their shoes" is to give them something of which they have at least some experience and have had some time to think about. One example, since many schools host TV shows of Space events and a few even have had a Q&A period for kids to ask astronauts questions. After you have filled a beaker in class maybe ask them what would be different if an astronaut performed the same action outside the capsule, or if a diver did this underwater. This might show a progression of densities that would send them in the right direction.
     
  18. Oct 29, 2014 #17

    sophiecentaur

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    Gold Member

    The Particle view of things is not intuitive and it can be a hard battle to get kids to accept that nothing is continuous - especially when we deal with most problems by assuming that it is. But kids know all about inconsistency in life - they will cope.
    If you want to get the idea of 'nothing' between particles, you could challenge the automatic view about air being there by asking them if they could breathe in deep space - where there is about 1m between particles. If there were air in between then they would be able to breathe.
    You problem here is that you need to convince some Adult Observer that you are getting the ideas across to the kids. This observer comes into the room with more preconceptions than the kids do (about both Science and Education). Annoying as it may seem, it may be better to go for a 'safe' approach, when you are being observed, along with a well accepted argument. It will depend on how interactive your kids are prepared to get. Once you have a good argument going then the ideas will flow - and when the Observer will be impressed. You need several different shots in your locker, in addition to your prepared resources. (OMG, I am so glad to be out of that Observation stuff. You have my sympathy).
     
  19. Oct 29, 2014 #18
    Yeah, at least my observer is super nice though. I feel pretty prepared.

    I think the "Students Questions for Purposeful Learning" technique will pique their interest with my fact (which i tell them may or may not be true and they have to come up with questions to find out whether it is true or not).

    "All Mater- solids, like this table in front of me, Liquids, like the water in a cup, and gases, like the air in this room, have significant portions of absolutely empty space occupied between their particles. Gases more so than liquids, and liquids more so than Solids."

    Hopefully this will spur good questions and thought. After they have the questions, I will tell them we are doing a lab (with inquiry based questions) to prove if this fact is true or not, and to answer their original questions about the fact.

    Also the lab they do will throw them into cognitive dissonance as they come up with theories as to why the volume is reduced. After that, all I have to do is discuss with them their findings and see if they are happy with my teacher "Fact". During this time, I may explicitly ask what they think is between particles in the drawing of a model.

    Once they are happy, we can write a poem or free write about the concept of nothing, which will let me see their thinking and give the students a chance to reflect on their understanding of "nothing" between the particles.

    Thanks for the sympathy though, it is a little nerve racking.
     
  20. Oct 29, 2014 #19
    But the idea that you have air between molecules is a contradiction of sort. Air is also made from molecules. So you will have some particles between other particles. It did not respond to the question "what is between atoms". And is not even relevant.
    If everything is made from molecules (atoms), you cannot have anything between them. With the exception of other atoms (molecules).

    Not talking here about fields, of course.
     
  21. Oct 29, 2014 #20
    I think you have missed the entire point of this thread....which was to help kids understand

    Yet, kids still have a hard time understanding that air isn't between air particles, no matter (pun not intended) how contradictory or ridiculous saying air is between air particles might sound.
     
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