Chapter 25 and 26 - Radioactivity and Nuclear Physics Flashcards
How is radioactive decay random?
We can not predict when a nuclei will decay and every nuclei in a sample has the same chance of decaying
How is radioactive decay spontaneous?
The decay of nuclei is not affected by external factors
What is the half-life of a substance?
The average time it takes for half of the active nuclei to decay
What is the activity of a radioactive source and what is it measured in?
The activity is the rate at which nuclei decay. Measured in becquerel (Bq), where 1 Bq is one nuclei decay per second.
Define decay constant
The probability of decay of an individual isotope nucleus per unit time.
Activity / Number of nuclei
Define mass defect of a nucleus
The difference between the combined mass of the individual nucleons and the mass of the nucleus
Define binding energy of a nucleus
The minimum energy required to completely separate a nucleus into its constituent protons and neutrons
What is the purpose of the coolant in a nuclear reactor?
To remove the thermal energy produced from the fission reactor
What is the role of a moderator in a nuclear reactor?
To slow down the neutrons so that they are able to be absorbed by other nuclei
What is the role of the controls rods in a nuclear reactor?
Absorb neutrons so that you can control the rate of the chain reaction in the reactor
How can you find the energy released from a fission/fusion reaction?
The difference in binding energy between the particles at the start and the particles at the end
What is induced nuclear fission?
When nuclei absorb neutrons causing them to become unstable. The nuclei then split creating two smaller nuclei and realising neutrons and energy. The released neutrons can then go on to be absorbed by other nuclei, causing a chain reaction.
What is nuclear fusion?
Getting two nuclei close enough together by giving them a large amount of energy so they can get close enough together so that the strong nuclear force pulls them together, overpowering the electrostatic force pushing them apart.
Why does nuclear fusion release energy?
By putting two particles together, it creates a difference in binding energy as the separate particles combined binding energy is lower than that of the new particle. This difference in binding energy is then released.
