Radioactivity and Nuclear Power Flashcards
What are nucleons?
Protons and neutrons, the particles in the nucleus.
What holds the nucleus together?
The strong nuclear force.
For heavier elements, do protons outnumber neutrons or the other way around in the nucleus?
Neutrons outnumber protons.
Why do some undergo radioactive decay?
To achieve greater stability.
What are the three types of radioactive decay we studied?
Alpha, beta and gamma decay.
Which of the three types of radioactive decay are unaffected by a magnetic field, alpha, beta or gamma?
Gamma.
Which of the three types of radioactive decay has the most mass, alpha, beta or gamma?
Alpha.
A beta particle is also known as a(n) __________
Electron
Which of the three types of radioactive decay has the greatest penetrating power, alpha, beta or gamma?
Gamma
Isotopes of an element are chemically identical but differ in the number of __________
Neutrons
A hydrogen atom with one neutron is called ________
Deuterium
The time needed for half of the radioactive atoms in a sample to decay is called a ___________
Half-life
True or False. Rates of radioactive decay appear to be absolutely constant, unaffected by any external conditions.
True.
If a 24-gram sample of a radioactive substance with a half-life of 7 days decays over 3 weeks, how much is left?
3 grams.
Which of the three radioactive decay modes - alpha, beta or gamma - creates an isotope of a different element?
Alpha and beta
Which of the three radioactive decay modes - alpha, beta or gamma - creates an isotope of an element with a higher atomic number?
Beta
Scientists can figure out how long ago a plant or animal died by measuring _________ of carbon-14 to carbon-12 in the remains.
The ratio.
True or false. Carbon dating can be used to determine how long ago a dinosaur lived.
False. Carbon dating can only be used for samples 50,000 years old at the most. Dinosaurs died out 65 million years ago.
Each year, we are exposed to natural radiation from ______
Cosmic rays, minerals from the Earth and radon gas.
The ago of the Dead Sea Scrolls was found by carbon dating. Could this technique work if they were instead stone tablets?
No because carbon dating only works on things that were once alive.
The splitting of atomic nuclei is called nuclear _______
Fission.
A situation where one reaction event stimulates one or more additional reaction events to keep the process going is called a _______________
Chain reaction
Which uranium isotope undergoes fission - U-235 or U-238?
U-235
True or False. Uranium ore contains much more U-235 than U-238.
False. Uranium ore contains only about 0.7% U-235.
What do you call the amount of mass for which each fission event produces, on the average, one additional fission event?
Critical mass.
Uranium samples must be ______ in order to sustain a chain reaction.
Enriched (increase the percentage of U-235)
In order to keep the nuclear reactor from overheating, the chain reaction is regulated with _____________.
Control rods
Control rods regulate the chain reaction by __________
Absorbing neutrons.
Breeder reactors convert non-fissionable uranium isotope into fissionable ___________ isotope.
Plutonium
When light nuclei are combined, the process is called _________
Nuclear fusion
True or False. Gram for gram, fission produces more energy than fusion.
False.
What is the biggest obstacle to controlling nuclear fusion?
Extremely high temperatures are needed
What would be the benefits to nuclear fusion as a power source?
No radioactive waste, more energy per gram, cheap and virtually unlimited fuel.
Why are there no appreciable deposits of plutonium in Earth’s crust?
The vast majority of plutonium atoms have radioactively decayed into isotopes of other elements.
