Radioactivity Flashcards
What is atomic number?
The number of protons in a nucleus
What is atomic mass number?
The number of nucleons (protons&neutrons) in a nucleus
Which part of the atom contains most of the mass?
The nucleus
What are an element’s chemical properties defined by?
Its atomic number (Z)
What is ionisation?
The process of removing or adding an electron to an atom
What is excitation?
An electron gains enough energy to move to an outer shell (but not leave), leaving a vacancy which an electron fills, releasing a photon as it drops
After particle emission, a nucleus may have excess energy which is emitted as a gamma ray
What is an isotope?
An atom of an element that has a different number of neutrons
Same Z, different A
What is an isobar?
An atom with the same number of nucleons as another
Same A
What is an isotone?
Atom of an element with the same number of neutrons
Same A
What does the stability of a nucleus depend on?
The proton/neutron ratio
What happens regarding stability of a nucleus as the number of protons increases?
More neutrons are needed to maintain stability
What is radioactivity?
The process whereby some nuclides undergo spontaneous changes in the structure of their nuclei, resulting in particle and radiation emission
What is a disintegration?
Each time the radioactive nucleus rearranges itself is called a disintegration
What is activity?
What is the SI unit?
What is the unit used in practice?
The rate at which a radionuclide undergoes disintegrations
(disintegrations per second)
SI unit = Becquerel (Bq)
Practice unit = Mega Becquerel (MBq)
Is disintegration random or planned?
Disintegration is a random process
