Do atoms behave like waves? I've heard someone state that the double slit experiment can also be done with atoms, not just electrons or photons of light.
 A: This is just a short expansion of Ernies comment (answer really) above, same  reference, and  the only thing I want to add is the size of the molecules, not just atoms but 58- and 114-atom molecules, made of links of carbon, hydrogen and nitrogen.
$\mathrm{C}_{60}$ Fullerene Double Slit experiment and Neutron Interference Pattern  both provide details of larger sized objects being used in the  Double Slit experiment.
A: Atoms do in fact have a sort of wave behavior you might say. Everything with mass does, even you! When the mass is small enough, like that of an electron or an atom, this behavior becomes more important to take into consideration. For example, when we go to look for an atom by shining light of a small wavelength on it, we can only say with a certain probability of where we think it's likely to be. This probability of where it's likely or unlikely to be found is described by a wave function. That is, a function which has different values for different locations in space. 
Unlike a water wave function which might tell you the height of water at various locations, the quantum wave function lets you know how high the probability of finding the particle is at various locations. 
