Unit 2: 7 - Energy From The Nucleus Flashcards
What are the 2 isotopes most commonly used in fission reactions?
Uranium-235 and Plutonium-239
What is nuclear fission?
The separation of an atomic nucleus
What is the most common naturally occurring uranium element? What is the problem with it?
Uranium-238. It is non-fissionable.
What is the special name used for the substance used in uranium reactors?
‘Enriched’ uranium, which contains about 2-3% uranium-235.
For fission reactions to take place, a _______ must be _______ at the unstable nuclei.
A neutron must be fired at the unstable nuclei.
What does the nucleus split into?
2 daughter nuclei, and some neutrons get ejected. (3 in the case of uranium)
The energy released in nuclear fission is much _____ than that of chemical reactions.
Greater
The splitting of a nucleus begins a ______
Chain reaction
What is nuclear fusion?
The process of forcing 2 nuclei close enough together to create a new nucleus.
In what natural process does nuclear fusion take place?
The energy release in stars
What are the conditions required for nuclear fusion?
Very high temperatures, around 8 million degrees Celcius.
What is a problem with nuclear fusion and how is it overcome?
Both nuclei have a strong positive charge to repel each other. Nuclear fusion requires the nuclei to be moving incredibly fast.
What type of radiation does radon gas emit and why is this dangerous?
Alpha, and as it gets in through the lungs. This is dangerous as it is most ionising.
What is a major source of background radiation?
Radon gas
Give 3 ways workers in a nuclear power station could reduce the exposure to nuclear radiation.
- Keep as far as possible from the sources
- Spend as little time exposed as possible
- Shield themselves with materials such as concrete and lead
Why must radioactive waste be stored securely?
Because it will still be unstable for many years emitting harmful radiation.
When was the universe created and by what process?
The Big Bang, 13 billion years ago.
After the first few minutes after the Big Bang, the _____ of the _____ elements formed.
The nuclei of the lightest elements formed.
When the universe first came into existence, the _____ was very high. The _____ then fell over millions of years.
Temperature
After the Big Bang over millions of years, ____ ____ were formed.
Uncharged atoms
Before galaxies and stars were formed, the universe was a dark patchy cloud of _____ and _____.
Hydrogen and helium
Dust and gas were pulled together by ____ ____ then _____ _____ to form stars.
Electrostatic forces then gravitational attraction.
The resulting intense heat from the transfer of ____ energy to ____ energy during _____ _____ started ______ ______.
The resulting intense heat from the transfer of kinetic energy to heat during gravitational attraction started nuclear fission.
What is a galaxy?
A very large group of stars.
