Summary
the nucleus of the atom has an internal structure
radioactivity is a nuclear effect rather than an atomic one
three type of radiation: ?(helium nuclei) , ? (electrons) and ?(photons)
nuclei are composed of protons and neutrons
isotopes of an element differ by the number of the neutrons in the nucleus
radioactive decays are spontaneous, obey the known conservation laws and most often change the chemical nature of their atoms
two factors determine the activity of a radioactive sample:
the number of radioactive atoms, and the characteristic half-life
all radiation interacts with matter depositing energy in the material leading to temperature increase, atomic excitation and ionization.
The ionization caused by radiation passing through living tissue can kill or damage cells.
Home work assignment : 637/1-9,13-21; 638/22-33,35-38
638/41-43,45-48; 639/51,54-57,9-16; 640/17,18