RADIOACTIVITY
Radioactive decay generally involves the emission of a charged particle or the
capture of an electron by the nucleus to form stable nuclides.
The amount of decay = The number of nuclear transformations per second.
Nearly all the nuclides in the world are stable.
Apart from hydrogen, all the stable lighter nuclei contain equal numbers of protons
and neutrons.
Heavier nuclei contain proportionately more neutrons.
Nuclides with the same atomic number but different atomic Mass are called
Isotopes.
Unstable nuclei ( with a neutron excess or deficit ) are radioactive and decay
(transform) until they become stable with emission of any combination of radiation:
Alpha
Beta
Gamma – High energy photons released from an excited
nucleus
Positron
K – Electron capture
Common terms used in this chapter :
Nuclide : Nuclear species with specific number of neutrons and
protons that exist in a defined nuclear energy state( 99mTc
is a different nuclide to 99Tc).
Radionuclide : Radioactive nuclide.
Metastable radionuclide : A radionuclide that exist for a long time in a higher energy
state before falling to ground state ( 99mTc).
Isomer : The metastable version of a nuclide (isomer ) of a nuclide.
(eg. 99mTc is an isomer of 99Tc).
Isotone : Nuclides with the same number of neutrons (isotone) but
with a different number of protons .
Isotope : Nuclides with the same number of protons (isotope) but with
a different number of neutrons.
1 WINTER GREEN ACADEMY
, The number of protons determines the element of an atom. You can change the number of
neutrons and the atom will still be the same element.( means change the mass number ).
RADIOACTIVE DECAY
The decay of a nuclide is exponential i.e, it theoretically never reaches zero.
The SI unit of radioactivity is Becquerel (Bq).
1 Bq = 1 transformation per second
TYPES OF RADIATION
When nuclide undergoes radioactive decay it breakdown to fall into a lower energy state
expending the excess energy as radiation. The radioactivity released can be :
Alpha particles
Beta particles
Gamma particles ( or Photons )
Others
Alpha particles
Symbol : α
Formed of 2 protons and 2 neutrons ( i.e, a Helium atom 2He4)
Positively charged
Relatively heavy
Short range of travel ( low penetration power)
High ionization power
Beta particles
Symbol : β
Electrons emitted from radioactive nuclei
Carry negative charge
Split into β- ( Negatron ) and an antimatter equivalent β+ ( Positron )
Lighter and smaller than Alpha
2 WINTER GREEN ACADEMY
Radioactive decay generally involves the emission of a charged particle or the
capture of an electron by the nucleus to form stable nuclides.
The amount of decay = The number of nuclear transformations per second.
Nearly all the nuclides in the world are stable.
Apart from hydrogen, all the stable lighter nuclei contain equal numbers of protons
and neutrons.
Heavier nuclei contain proportionately more neutrons.
Nuclides with the same atomic number but different atomic Mass are called
Isotopes.
Unstable nuclei ( with a neutron excess or deficit ) are radioactive and decay
(transform) until they become stable with emission of any combination of radiation:
Alpha
Beta
Gamma – High energy photons released from an excited
nucleus
Positron
K – Electron capture
Common terms used in this chapter :
Nuclide : Nuclear species with specific number of neutrons and
protons that exist in a defined nuclear energy state( 99mTc
is a different nuclide to 99Tc).
Radionuclide : Radioactive nuclide.
Metastable radionuclide : A radionuclide that exist for a long time in a higher energy
state before falling to ground state ( 99mTc).
Isomer : The metastable version of a nuclide (isomer ) of a nuclide.
(eg. 99mTc is an isomer of 99Tc).
Isotone : Nuclides with the same number of neutrons (isotone) but
with a different number of protons .
Isotope : Nuclides with the same number of protons (isotope) but with
a different number of neutrons.
1 WINTER GREEN ACADEMY
, The number of protons determines the element of an atom. You can change the number of
neutrons and the atom will still be the same element.( means change the mass number ).
RADIOACTIVE DECAY
The decay of a nuclide is exponential i.e, it theoretically never reaches zero.
The SI unit of radioactivity is Becquerel (Bq).
1 Bq = 1 transformation per second
TYPES OF RADIATION
When nuclide undergoes radioactive decay it breakdown to fall into a lower energy state
expending the excess energy as radiation. The radioactivity released can be :
Alpha particles
Beta particles
Gamma particles ( or Photons )
Others
Alpha particles
Symbol : α
Formed of 2 protons and 2 neutrons ( i.e, a Helium atom 2He4)
Positively charged
Relatively heavy
Short range of travel ( low penetration power)
High ionization power
Beta particles
Symbol : β
Electrons emitted from radioactive nuclei
Carry negative charge
Split into β- ( Negatron ) and an antimatter equivalent β+ ( Positron )
Lighter and smaller than Alpha
2 WINTER GREEN ACADEMY
