Nuclear Fission And Nuclear Fusion Flashcards
What is the atomic mass of an element
The total number of neutrons and protons it’s the bigger number
What is the atomic number of an element
The amount of protons usually the smaller number
What are isotopes
Different forms of the same element
The have the same number of protons but different numbers of neutrons so the same atomic number but different mass numbers
What is radioactivity
Unstable nuclei decay and give out ionising radiation
It is completely random
And in the process the nucleus often changes into a new element
How does alpha ionise
Large positive charge
They pull electrons from the orbit of the atom
What is ionisation
When an atom loses or gains an electron the charge changes and it becomes an ion
How does beta ionise
They are negatively charged so the repel an electron off of the atom
How do gamma rays ionise
They give energy to the electrons by orbiting the atom which allows the electron to break free
What are alpha particles
Helium nucleus Two protons and two neutrons Big heavy and slow moving Strong positive charge Strongly ionising Weakly penetrating
What are beta particles
They’re electrons emitted from a nucleus
They move quite fast and are quite small
They have a negative charge
Moderately ionising
Moderately penetrating
For every beta particle emitted a neutron turns into a proton in the nucleus
What are gamma rays
They’re waves
They’re weakly ionising
Strongly penetrating
What blocks the three types of radiation
Alpha paper
Beta aluminium
Gamma lead or concrete
What is nuclear fissio
The splitting up of uranium atoms
A neutron is fired at an isotope of uranium and is absorbed by the nucleus this makes the atom unstable and causes it to splint
Two new lighter daughter nuclei are formed and heat energy is released
The new nuclei are always unstable so radioactive and new neutrons are released which can be absorbed by more uranium nuclei causing a chain reaction
How do nuclear power stations work
A controlled chain reaction of nuclear fission takes place in the reactor and the heat energy is used to boil water to get steam to power the turbines and create electrical energy
How are the chain reactions controlled
The uranium fuel rods are placed in a moderator eg water to slow down the neutrons so they can undergo nuclear fission
Control rods made of boron absorb excess neutrons to limit the rate of fission they can be raised an lowered to control the rate of reaction
If there were no control rods then the reaction would run away and cause an explosion like in Chernobyl
What is nuclear fusion
Two light nuclei join at speed and fuse to create a larger nucleus
There’s no radioactive wast left behind and much more energy is produced than fission
What is the problem with nuclear fusion
It only happens at really high temperatures and pressures
The reactors would be really hard and expensive to build if it could withstand the high temperatures as pressures
It takes more power to get the right temperature than the reaction would produce
How are scientists trying to improve nuclear fusion
Cold fusion is nuclear fusion that occurs at room temperature but the results are not reliable enough yet to be used
