Unit 1.4 Flashcards
Define Radioactive Decay; what are the two units used?
The spontaneous nuclear transformation in an unstable atom to result in a new element. Decays per second are known as Becquerel; 3.7 x 10^10 Bq are 1 Curie (Ci).
Define Radioactive Half life.
The time for the activity of a radioactive element to decrease by one-half by radioactive decay.
Define Biological Half Life.
The time required for the body to eliminate by natural biologic means 50% of the material taken into it.
Define Effective Half Life.
The time required for a radioactive element in the body to be diminished by 50% as a result of the combination of Biologic and Radioactive half lives.
SOLVE radioactive decay and specific activity problems.
Going to have to go through these.
Describe alpha particle emission.
A proton rich nucleus releases an alpha particle (2 protons, 2 neutrons) due to having a low neutron to proton ratio. The process is accompanied by 2 electrons released due to the alpha particle having a +2 charge.
Describe beta minus particle emission.
A neutron is converted into a proton, a b- particle, and an antineutrino. The beta and antineutrino are emitted as radiation while the daughter nucleus is sometimes left in an excited state and further de-excites via gamma emission except in “pure beta emitters.”
Describe beta plus particle emission.
This happens only if a minimum of 1.022MeV energy difference exists. A proton is converted into a neutron, a b+ particle, and a neutrino. The beta and neutrino are emitted as radiation while the daughter nucleus is sometimes left in an excited state and further de-excites via gamma emission.
Describe the annihilation reaction that completes the life cycle of a beta particle.
After a Beta+ particle slows down, it combines with an electron in an annihilation reaction destroying both particles and creating two gamma rays, released in opposing directions with an energy of 0.511 MeV.
Explain the process of electron capture.
Ann inner shell electron is pulled from orbit by the nucleus and combines with a proton to create a neutron. This competes with beta plus decay but does not require 1.022 MeV. A neutrino is released in the process.
Define Isomeric Transitions and 2 examples.
The atomic number and mass number of the daughter nucleus is the same as the parent nucleus. This is gamma ray emission, metastable decay, and internal conversion.
Describe Gamma ray emissions.
Stabilizes an excited nucleus by emitting extra energy in the form of a gamma ray. This can happen immediately or be delayed (metastable).
Describe Metastable Decay
Isomeric transition (same atomic number) with gamma ray release longer than 1 microsecond. The daughter nuclide persists in the excited ‘meta-stable’ state until the energy is released as a gamma ray.
Explain Internal Conversion.
When the daughter nuclide is left in an excited state, the extra energy of the nucleus can be transferred to the electron could and one of the electrons can be ejected.
