many undeflected α-particles many deflected by very small amounts α-particles a few deflected by angles > 90o α-particles a few deflected bounced back α-particles Rutherford backscattering (RBS) Conclude +ve charge of atom concentrated at tiny core mass of atom concentrated at tiny core rest of atom almost empty Analysis nuclear radius ~ 10-14 m nuclear density ~ 1017 kg/m3 Problem with nuclear model: what holds protons together in nucleus? where are the electrons? what gives solids their structure? 3. Atomic spectra light emitted from excited gas comprises a discrete line spectrum each element has its own characteristic spectrum Hydrogen spectrum: described exactly by Rydberg-Ritz formula
many α-particles undeflected many α-particles deflected by very small amounts a few α-particles deflected by angles > 90o a few α-particles deflected bounced back Rutherford backscattering (RBS) Conclude +ve charge of atom concentrated at tiny core mass of atom concentrated at tiny core rest of atom almost empty Analysis nuclear radius ~ 10-14 m nuclear density ~ 1017 kg/m3 Problem with nuclear model: what holds protons together in nucleus? where are the electrons? what gives solids their structure? 3. Atomic spectra light emitted from excited gas comprises a discrete line spectrum each element has its own characteristic spectrum Hydrogen spectrum: described exactly by Rydberg-Ritz formula
f2introduction-to-particle-physics2.docx