A Gas Model Made of Magnets

Magnets are great stuff and everyone loves them, there are so many things you can do with them, including creating a model of the crystalline structure of solids, just as [Cody´s Lab] did using a bunch of magnets inside a pair of plexiglass sheets.

Crystal structure of ice. Image from Wikemedia Commons.

Many materials have their atoms arranged in a highly ordered microscopic structure — a crystal — including most metals, rocks, ceramics and ice, among others. The structure emerges when the material solidifies looking for the minimum energy configuration. Every atom interacts with its neighbors via microscopic forces forming several patterns depending on the specific material and conditions.

In his macroscopic world, [Cody´s Lab] used the magnets as his “atoms” and the magnetic repulsion between them represent the microscopic forces. Confining the magnets inside two transparent walls, one can see the formation of the crystal structure as magnets are added one by one.

This is an excellent teaching resource and also a fun way to play with magnets if you want to give it a try. Or if you want another magnet hack, we have tons of them, including implanting them in your body, or making your own with 3D printing.

16 thoughts on “A Gas Model Made of Magnets

  1. Excuse the language, but this is FUCKING BRILLIANT. I believe your incredible visualization will be used for years to come to teach chemistry and the understanding of how atoms interact in a way the students can touch and feel. I believe this is an historic “discovery” of a tool for the visualization of how elements interact. Bravo!!! you get the seldom-earned “slow clap” (think officer and a gentleman movie). Well done. My kids (in 8 years) thank you for making chemistry more fun than it already is.

    1. It’s not structured enough for a crystal structure. There is another video that deals with crystal structures and their properties in a similar simple and intuitive way, though:

    2. It doesn’t work that way. A crystal is an ionic bond and molecules are covalent. If the glass is laid flat it is more gas-like. A crystal will shear when a force offsets a line of atoms by 1/2 the lattice spacing and all the attractive forces are replaced by repelling forces, which this scheme will not do.

      1. That isn’t completely correct either. Crystal is any solid with well defined periodic structure. Covalent crystals exist too, for example diamond and quartz. You also might like to check “crystal defects”, as planar defects aren’t always destructive.

        But you are correct, this isn’t crystal model. It isn’t a very accurate model of anything. If I should describe it, I would call it a liquid/gas model of noble gas atoms, without thermal and phase properties.

        It’s a shame really that the thermal and acoustic properties are lost due to the huge friction between the magnets and the plexi glass. Not really sure if you could lubricate the system effectively.

        1. IMHO also that analogy to a nobel gas is quite incorrect. Nobel gas atoms interact via Van-der-Waals-forces, which have an exponential decay with distance. So they have contact forces and not long-range forces. This means that nobel gas atoms are best viewed as something like “a heap of tennis balls bouncing around”. But the author of the video apparently believes that very-densely-packet magnetically repulsing circles are a *better* model of a gas than very few non-repulsing, solid spheres. This is what I find the *most misleading* implicit statement of this video. In fact, in physics we say that a gas is ideal if there are exactly *no* interactions. So you may ask, then what generates the gas pressure in an ideal gas? Well, that is caused only by the fact that gas atoms are in constant motion at nonzero temperature. The tiny impulses transferred to the “walls” at each reflection of a fast-moving atom generate the pressure of an ideal gas. (By the way, this explains nicely why the ideal gas pressure and volume approaches zero at zero temperature)

          In conclusion, it’s absolutely not a gas, and (as Pel said) its certainly also not a solid of any kind (e.g. also not a crystal). The main point why its certainly not a solid is that it cannot sustain negative pressures (e.g. pulling of the walls) from the outside, and the underlying reason for this is that all particle-particle forces in the system are all repulsing, and not attracting. The closest physical system is possibly a highly-charged plasma which is extremely strongly contracted by its own gravitational weight. Probably such a system exists at the surface of a neutron star ;-)

  2. I’m no expert in this field but this is to me a very intuitive and logical demonstration of something that would otherwise be impossible to view with your own eyes and interact with in real time.Even if people don’t want one (because of the potential problems that these strong magnets can create), the video in itself is very clear.
    Brilliant! Thanks for posting.

  3. This is a brilliant demonstration,
    Also this video accidentally included a demonstration of an added molecule being heavier than the single “atom” magnets due to one magnet being the wrong way and attracting some neighbors thus demonstrating a molecule and “Chemical reaction” so to speak.

    Also shows that the heavier molecule didn’t quite sink straight to the bottom, the same as some CO2 is absorbed into the air (like the air is a sponge, IRL usually before the rest sinks due to saturation i’d guess)

    Though it seems to behave more like a dense liquid than a gas. Still full of neat demonstration of air none the less

  4. Normally, the more abstract electromagnetic properties of atoms and molecules are ignored and they are often portrayed as hard particles. I love that this models the electromagnetism by using actual magnetism. That makes imagining things on a smaller scale much more intuitive.

  5. After being a CodysLab sub and daily HAD reader, I’m actually surprised that this is the first I have seen of Cody’s work on HAD. Check out his other videos. Most of them are right up the ally of the (not-so-average) hacker.

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