unit cell(smallest repeating structure in crystal) noun [UK: ˈjuː.nɪt sel] [US: ˈjuː.nət ˈsel]
particella elementarenoun {f}
elementary particle [elementary particles](subatomic particle that does not consist of smaller particles) noun [UK: ˌel.ɪ.ˈment.ər.i ˈpɑː.tɪk.l̩] [US: ˌel.ɪ.ˈment.ər.i ˈpɑːr.tək.l̩]