Name two substances that are commonly used as fuel in nuclear fission reactors
uranium-235
plutonium-239
What is the name of the process whereby a nucleus is split into smaller parts
Nuclear fission
Which particle must be absorbed by uranium-235 or plutonium-239 for fission to occur?
A neutron
What is produced when an unstable nucleus splits into two smaller nuclei?
Energy, and 2 or 3 neutrons
What is nuclear fusion?
The joining of two atomic nuclei to form a larger one
What is the name of the process by which energy is released in stars?
Nuclear fusion
What force pulls together dust and gas within nebulae?
Gravity
What is the name given to the stable part of a star's lifecycle?
Main sequence
What determines the lifecycle path of a star?
Its size
Where are elements up to the mass of iron formed?
By a star in its stable period
How are all the naturally occurring elements produced?
By fusion processes (either during a stars main sequence or during a supernova at the end of its life)
What name is given to a star before it starts its main sequence?
Protostar
What is left at the end of the biggest stars life?
Black hole
What does a star the same size as the Sun become immediately after its main sequence?
Red Giant
Put these into the correct sequence for a star like our sun: white dwarf black dwarf protostar red giant main sequence nebula
Nebula => protostar => main sequence =>
red giant => white dwarf => black dwarf
What is a supernova?
An explosion at the end of the life of a large star
What is the role of the moderator in a fission reactor?
It slows down the neutrons so that they are slow enough to be absorbed by nuclei (and so continue the chain reaction)
How is a nuclear fission reactor controlled?
By the use of control rods which can be inserted to absorb neutrons and so slow down the chain reaction
Why is nuclear fusion hard to achieve?
The positively charged nuclei will repel each each other and overcoming this requires a large amount of energy.
How are planets formed?
Matter from a protostar may not all become part of the star. The remainder will eventually be drawn together by gravity to form planets, moons, asteroids and comets.
The most common fuel in the sun is Hydrogen. Which two isotopes of hydrogen fuse to form Helium?
