P2.6 Nuclear fission and nuclear fusion Flashcards
What are the most commonly used substances in nuclear fission?
Uranium-235 and Plutonium-239
What is nuclear fission?
The splitting of an atomic nucleus
For fission to occur, what must the uranium and plutonium do first?
Absorb a neutron
What happens in nuclear fission?
A neutron is fired at the neutron. The neutron then splits into two smaller nuclei and two or three neutrons and energy are released. These neutrons released then go on to hit more nuclei which then split and so on
What is nuclear fission?
A controlled chain reaction
What is an example of an uncontrolled chain reaction?
A nuclear bomb
What is nuclear fusion?
The joining of two atomic nuclei to from a larger one
What is nuclear fusion the process of?
How energy is released from stars
How do stars form?
When enough dust and gas from space is pulled together by gravitational attraction
How may planets form?
Smaller masses may form and be attracted to a larger mass and become a planet
Why did the early universe only consist of hydrogen but now a large variety of other elements?
During most of a stars lifetime hydrogen is fused to form helium. When the star runs out of hydrogen, other fusion reactions take place forming other elements. Elements up to iron are formed, and elements heavier than iron are formed in supernovas
During the main sequence period of a star’s lifecycle it is stable, why?
Because the forces within it are balanced
What is the star’s life cycle determine by?
Its size
What does a protostar turn into?
A main sequence star
What does a star about the same size as the sun turn into after being a main sequence star?
It expands to become red giant
