In this lecture you will learn:
|Scientists noticed that when the hydrogens
were fused to make helium the resulting mass of protons and neutrons
in helium were smaller than the sum of the hydrogen nuclei that
went into making the helium. This is called THE MASS DEFECT
The decrease in mass is not lost, it is converted to energy and
1. part is used to bind the nuclei together (those pesky protons with their positive charge) (the strong force) and
2. some is released ... that is the energy
spewing out of the sun and fueling life on earth
|MORE ON THE MASS DEFECT - the graph on
Helium + other nuclei are fused to make elements higher up the periodic table until iron is reached. Until iron the nuclei LOSE mass which is converted into energy. The fusion of hydrogen yields the most energy.
Once iron is reached the mass of the fusion products begins to increase so an input of energy is required to form the extra mass.
The nuclei of elements that are naturally radioactive or that can be made to be radioactive can split or lose protons and neutrons and they give up energy as a result, this is fission. The amount of energy is small compared to fusion.
In Einstein's theory of relativity, mass and energy are the same thing, they are just different forms. E=MC*2 is the relationship between them.
|where do we find enough energy to fuse
the nuclei of smaller elements, adding enough energy to make heavier elements?
Compare fusion and fission.
Describe the relative amounts of energy released by fusion vs fission. Draw the curve.
Discuss where and how all the heavier elements come from and are formed?
Discuss how our Sun provides the Earth with energy.
Fusion occurs until what element is reached?
The mass of protons and neutrons are larger in hydrogen nuclei than in helium nuclei. What happens to the lost mass?
What are two origins of energy in the universe?
What are the two main sources of heat on Earth?
What holds protons together?
What is the source of energy in fusion?
What is fusion?
What is the mass defect?
What happens in massive stars when iron starts fusing?
What causes a supernova?
What is plasma? What conditions are necessary for fusion to occur? What part of the atom is not present in plasma?
What part of the atom is involved in fusion?
Where does the energy of mass defect go?