I know Chadwick found/discovered the neutron, but my textbook does not state what experiment he did to find it. Can someone briefly state what he did to find the atom?

Here is a link. It is quite similiar to the Rutherford's gold foil experiment for the proton.

http://dev.physicslab.org/Document.aspx?doctype=3&filename=AtomicNuclear_ChadwickNeutron.xml