22 - 23 Theory Flashcards
State law of electrostatics
Identical charges exert a repelling force on each other
What is nuclear force?
The force exits between nucleons that holds nuclear constituents together (pre- vent the repelling of identical charges, charge-independent)
What is mass defect?
The mass of a nucleus is less than the mass of its constituent nucleons.
(The reason the actual mass is different from the masses of the components is because some of the mass is released as energy when protons and neutrons bind in the atomic nucleu)
What are nucleons?
Protons and neutrons
What is binding energy of nucleons
The energy corresponding to the mass defect
What is Binding energy per nucleon?
The strength of a nuclear bond
What are isotopes
Atoms of the same element with
- the same number of protons
- different numbers of neutrons
- different mass number
Light nucleus are most stable when ____
N=Z
Heavy nuclei are most stable when
N>Z
Describe nuclear stability
As the number of protons increases, the Coulomb force increases and so more neutrons are needed to keep the nucleus stable
3 stability rules
(1) There are more stable nuclei with even, than with odd number atomic num- bers
(2) There are more stable nuclei with even, than with odd number neutron numbers
(3) There are more stable nuclei with even, than with odd number mass num- bers
What is radioactivity?
the spontaneous release of energy in the form of particles or electromagnetic waves
the result of decay of unstable nuclei
What is radioactive decay?
Spontaneous decay of unstable parent nucleus into a more stable daughter nucleus & constituents/particles & energy
What is activity of radioactive decay?
number of nuclei decayed in a unit time (characterizes the quantity and quality of radioactive substances)
State the law of radioactive decay
The rate of decay is proportional to the number of radioactive nuclei present.
What is specific activity?
activity in a unit mass of isotope (Bq/kg)