Nuclear fission and nuclear fusion Flashcards
What are the two commonly used fissionable substances in nuclear reactors?
Uranium-235 and plutonium-239.
What is nuclear fission, basically?
The splitting of an atomic nucleus.
For fission to occur what must first happen to uranium-235 or plutonium-239?
They must absorb a neutron.
What happens to a nucleus undergoing fission?
It splits into two smaller nuclei, two/three neutrons re released and energy is released.
What may happen to the neutrons released by fission?
They may go on to start a chain reaction.
Nuclear fusion is what, basically?
The joining of two atomic nuclei to form a larger one.
What nuclear process is used to release energy in stars?
Nuclear fusion.
Stars form how?
Dust and gas in space is pulled together by gravitational attraction.
Pressure increases and temperature increases.
There is enough energy for nuclear fusion to take place.
Smaller masses may be attracted by the star to become what?
Planets.
During the main sequence period of the life of a star what can be said about the forces acting on the star?
The star is stable and the forces acting upon it are balanced.
The life cycle of a star is determined by what?
Its size (mass).
Describe the life of a star the size of our sun or smaller.
Protostar. Main sequence star. Red giant. White dwarf. Black dwarf.
Describe the life of a star greater than the size of the sun.
Protostar. Main sequence star. Red supergiant. Supernova. Neutron star or black hole.
Elements up to what are produced in nuclear fusion in stars?
Elements up to iron.
When are all other elements produced?
During a supernova.
