Nuclear Transformations Flashcards
(78 cards)
Who discovered radioactivity and when?
Radioactivity was first discovered by Antoine Henri Becquerel in 1896.
What is radioactivity?
Radioactivity is a phenomenon in which radiation is given off by the nuclei of elements, in the form of particles, electromagnetic radiation, or both.
How can radiation emitted by radium be separated?
Radiation emitted by radium can be separated by a magnetic field, with α particles being positively charged and β− particles negatively charged, causing them to be deflected in opposite directions.
What are γ-rays?
γ-rays are similar to x-rays but have a nuclear origin and are unaffected by magnetic fields.
What is the decay constant?
The decay constant (λ) is a constant of proportionality in the mathematical description of radioactive decay.
What does the equation ΔN/Δt = -λN represent?
This equation represents that the change in the number of radioactive atoms per unit time is proportional to the number of radioactive atoms present.
What is the activity of a radioactive material?
The activity is the number of disintegrations per unit time, represented by A.
What is the SI unit for activity?
The SI unit for activity is the becquerel (Bq), defined as one disintegration per second.
What is half-life (T1/2)?
Half-life is the time required for either the activity or the number of radioactive atoms to decay to half the initial value.
What is the relationship between half-life and average life?
The average life (Ta) is related to half-life (T1/2) by the equation Ta = T1/2 / ln(2).
What is the specific activity of a radionuclide?
The specific activity is the activity per unit mass of a radionuclide.
What is transient equilibrium?
Transient equilibrium occurs when the half-life of the parent nuclide is not much longer than that of the daughter nuclide.
What is secular equilibrium?
Secular equilibrium occurs when the half-life of the parent nuclide is much longer than that of the daughter nuclide.
What is an example of secular equilibrium?
A radium source in a sealed tube is an example of secular equilibrium.
What types of radioactive decay are there?
There are several modes of radioactive decay, including α particle decay.
What is an example of secular equilibrium?
A radium source in a sealed tube or needle is an excellent example of secular equilibrium.
What type of decay do radioactive nuclides with very high atomic numbers (>82) most frequently undergo?
They most frequently undergo α particle decay.
What happens to the atomic and mass numbers during α decay?
The atomic number is reduced by 2 and the mass number is reduced by 4.
What is the disintegration energy in α decay?
Disintegration energy (Q) is the total energy released in the process, equivalent to the mass difference between the parent and product nuclei.
What is a typical example of α decay?
The transformation of radium to radon is a typical example of α decay.
What is β decay?
β decay is the process of radioactive decay accompanied by the ejection of a positive or negative electron from the nucleus.
What are the two types of electrons involved in β decay?
The negative electron (negatron, β−) and the positive electron (positron, β+).
What is the general equation for negatron emission?
The general equation for negatron emission involves a neutron transforming into a proton while emitting a β− particle and an antineutrino.
What is the significance of the neutrino in β decay?
The neutrino, which has no charge and practically no mass, is theorized to accompany each β particle emitted and share the available energy.
