Radioactivity
Henri Becquerel: strange rays coming from all uranium compounds --> should have a nuclear origin (not changed during chemical reactions, or different physical conditions)
the strength of the radiation depends only on the amount of uranium present
Pierre Curie and Marie Sklodowska Curie: thorium also radiates!
NEW radiating elements: polonium and radium
three different type of radiation identified:
- alpha (?) radiation: small penetration in objects, positively charged particles, 2X charge of an electron, 4X the mass of H, (He atom nucleus)
- beta (?) radiation: bigger, but still small penetration, negatively charged particles, mass and charge of the electrons, --> electrons!
- gamma (?) radiation: high penetration in all materials, no charge,
shown to be very high energy photons