Is Aluminum Magnetic?
In our everyday experience aluminum doesn't stick to magnets (neither does copper). The question of whether aluminum is magnetic is a bit more involved and depends what you mean by the term "magnetic".
Most matter will exhibit some magnetic attraction when under high enough magnetic fields. But under normal circumstances aluminum isn't visibly magnetic.
This is easily tested by putting a very strong neodymium magnet near aluminum can. They both just sort of site there.
If Aluminum Isn't Magnetic does it Do Anything Interesting?
Yes. Yes, it does.
Aluminum Pipes and Magnets
To really see this in action you can drop a strong magnet down an aluminum pipe. As the magnet moves down the pipe it creates small electrical currents in walls of the pipe. These electrical currents repel the magnet and cause it to fall slower. With larger pipes and magnets the effect is more dramatic.
The larger the magnet and pipe the more pronounced the effect.
It's difficult to find really thick pipes but thinner pipes will work. You need to make sure you have really strong magnets (neodymium rare earth magnets) and a few feet of aluminum or copper pipe to see the effect. The magnet should be fairly close to the size of the pipe for the best effect.
To see this taken to an extreme watch what happens when a tube of aluminum foil is put near the very strong magnetic field generated by a MRI machine (the M in MRI stands for Magnetic). Note how much fun the guy is having.
You can also see how slowly an aluminum pipe will fall though the magnet on an MRI.
Even though the magnet isnít attracted to the can, that doesn't meant that they cannot interact with each other. If you move the magnet over the can you can actually cause the can to rock back and forth and eventually role.
If you are concerned (and as a thoughtful scientist you should be) that air is causing the can to move you could try it with another object like an eraser or piece of wood. If you do you'll find the can doesn't move. So we can rule out wind as a major factor. Somehow the motion of the magnet is causing the can to move.
What is happening is that moving the magnet over the can caused small electrical currents to form in the aluminum metal. These currents interact with the moving magnet and cause the can to move. Windmills, power stations, etc. all use this same interaction to generate electricity (but they use copper instead of aluminum). In fact, any time you move a magnet around conductive metals you generate electricity.
So, Is Aluminum Magnetic?
The best answer is to say that it is not magnetic under normal circumstances. But it's always impressive to show them the can demonstration and how it can interact with magnets.
We can say that in strong magnetic fields aluminum can become slightly magnetic but in everyday experience it does not exhibit magnetism. It does, however, interact with magnets in very useful and interesting ways.