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  • This is a neodymium magnet - it's pretty darn strong.

  • And now, after heating it in a flame... it's no longer magnetic.

  • What just happened?

  • Well, to build a magnet, all you need to do is find a bunch of magnetic atoms (that's

  • easy - they're the ones with half-filled electron shells in the middle of any of the major blocks

  • of the periodic table) and then make a compound where the magnetic fields of the atoms align

  • in the same direction - this is Ferromagnetism, named after Iron, which is pretty darn magnetic.

  • However, it's not so easy - sometimes the atoms actually want to align their magnetic

  • fields in alternating directions - this is called "anti-ferromagnetism," and it means

  • the bulk material won't have a magnetic field at all.

  • Or, sometimes the tendency of the atomic magnets to align (or anti-align) is just too weak

  • to overcome their intrinsic jiggling - that is, their temperature!

  • In which case, even though all the individual atoms in the material are magnetic, once more

  • the material as a whole isn't.

  • However, in a strong external magnetic field, the atoms do tend to align with each other

  • in the direction parallel to the field.

  • This is called "para-magnetism," and liquid oxygen is a great example - it's attracted

  • by a magnet, though it doesn't stay magnetized afterwards.

  • But let's get back to the question - how do you destroy a magnet?

  • Well, a material can only be ferromagnetic if its temperature is low enough: above a

  • certain point, the nicely ordered atomic magnetic fields "melt" into disorder, just as ice crystals

  • melt into water when heated past zero celsius.

  • So to destroy a magnet, you just need to heat it up past its "magnetic melting point", called

  • the "Curie Temperature" - it probably won't look like much is happening, but once the

  • atoms are jiggling around enough, when they cool off, their magnetic fields will no longer

  • all point in the same direction.

  • Magnet destroyed!

  • And just as different elements melt from solid to liquid at different temperatures, they

  • also melt from being ferromagnetic to paramagnetic at different temperatures, which you can explore

  • in this sweet interactive periodic table.

  • Which also plays all

  • of

  • the Periodic Table

  • of Videos.

This is a neodymium magnet - it's pretty darn strong.

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