Why Metals Bend, Not Break

Materials engineering is the study of why stuff acts the way it does. Metals are special because of their atomic structure. Unlike brittle glass, metal atoms are arranged in a 'sea of electrons' that allows layers of atoms to slide past each other without breaking the bonds between them. This sliding action is called ductility. When you bend a paperclip, you are sliding these layers. If you do it too much, however, the atoms get 'locked' and lose their ability to slide, which is why the metal eventually snaps.