Rutherford set up a piece of gold foil and shot alpha particles into it. I want to pause here a minute and talk about gold foil. It's really cool. I've used it in a physics lab. Don't think of the aluminum foil in your kitchen.
Gold foil is very, very thin.
You have to handle it with tweezers. If you pick it up with your fingers, you'll never get it off your finger tip. It's just too thin. See, a sheet of gold foil is only a few atoms thick. And that's why scientists like to use it.