Nuclear Physics

1. Atoms and nuclei An atom has a tiny, positively charged nucleus surrounded by negatively charged electrons. Most of an atom is empty space. A neutral atom has equal numbers of protons and electrons. Losing electrons forms a positive ion; gaining electrons forms a negative ion. Alpha-scattering experiment Rutherford directed alpha particles at thin gold foil and used a surrounding screen to detect where they went. Most passed straight through; some deflected, and very few bounced back. Close approaches to the positively charged nucleus repelled the positively charged alpha particles. ...