atomic physics
Alpha-scattering experiment
neutrons (no charge)
protons (positive charge)
electron (negative charge)
Z+N=A
rytgerford-bohr model
when the electrons got excited, they may jump to an outer orbit
- the electrons circled the nucleus in certain orbits
ionization energy
nuclear energy
E=mc<2
Fission
fussion
radioactivity
radioactive decay
a unstable nucleus emits radiation in an attempt to become more stable, this is known as radioactive decay
background radiation
in fact we are exposed to low levels of radiation all the time
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β
γ
α
4 （2） He
0(-1)e
thick paper
a few millimeters of aluminum
many centimeters of lead
application
Medical diagnosis
Fault detection
thickness measurements
radiation therapy
smoke detectors
food irradiation