Fission and Fusion Flashcards
Why are some materials radioactive?
The nucleus of each atom is unstable and gives out nuclear radiation in the form of alpha particles, beta particles or gamma rays.
What is an isotope?
Atoms of an element with the same number of protons and electrons but different numbers of neutrons.
What is fission another word for?
Splitting
What is nuclear fission?
The process of splitting of a nucleus.
What happens when a uranium-235 or plutonium-239 nucleus is hit by a neutron?
The nucleus splits into two smaller nuclei – daughter nuclei, which are radioactive.
Two or three more neutrons are released.
Some energy is released.
What is a chain reaction?
The additional neutrons released from nuclear fission may also hit other uranium or plutonium nuclei and cause them to split. Even more neutrons are then released, which in turn can split more nuclei.
How is radioactive waste stored?
At present the most dangerous waste is sealed in glass-like blocks which are buried deep within rocks. Careless disposal of waste in the past has led to pollution of land, rivers and the ocean.
Explain nuclear reactors.
As well as producing heat the nuclear reactor can be used to make other materials radioactive. The chain reaction inside the reactor releases neutrons. If a material is put into the reactor some of these neutrons may be absorbed by the nuclei of its atoms. This will make an atom’s nucleus unstable which means it has become radioactive. These man-made radioisotopes are often then used as tracers in hospitals to diagnose and treat patients or in industry to detect leaks in pipes.
What is nuclear fusion?
When two atomic nuclei joining to make a large nucleus. .
Explain nuclear fusion.
Nuclear fusion involves a deuterium and a tritium nucleus colliding and being forced together. Both nuclei are positively charged and therefore will repel each other. This is known as electrostatic repulsion. The nuclei have to get very close in order to collide, which is approximately a million millionth of a millimetre. If the nuclei are moving very fast then they can overcome the electrostatic repulsion. The hotter a molecule is, the faster it will move and the more likely it is to collide.
What is cold fusion?
In 1989 Martin Fleischmann and Stanley Pons claimed to have carried out nuclear fusion at 50°C. This became known as cold fusion. It seemed to offer the possibility of an energy source at a reasonable temperature.
