Explain Nuclear Fission and Nuclear Fusion.
Nuclear Fission and Nuclear Fusion:
Isotopes: are atoms that have same atomic number (number of protons) but different mass numbers (numbers of neutrons) or both elements having the same atomic number.
Isobars: are atoms that have same mass numbers (numbers of neutrons) but different atomic number (number of protons) or both elements having the same atomic mass.
Nuclear fission: –
In nuclear fission process, the atom splits generating large amounts of energy; For example uranium (U-235) absorbs a neutron, fission occurs as it splits into two particles of uneven mass (smaller nuclei), huge amount of energy (~200Mev) with several neutrons. A chain reaction is produced as fission continues and the neutrons emitted bombard more uranium (U-235) nuclei. Experimentally, we find that spontaneous fission reactions occur for only the very heaviest nuclides those with mass numbers of 230 or more. Even when they do occur, these reactions are often very slow. The half-life for the spontaneous fission of U-238 is 1016 years. In these process isotopes of elements having atomic numbers greater than 80 are capable of undergoing fission and large amount of energy is released that an atomic explosion occurs. The Nuclear power plants operate under this principle.
A diagram of uranium-235 undergoing nuclear fission is shown below.
The nuclear fusion is reverse process of nuclear fission; i.e the nuclear fusion is the joining of two lighter nuclei and forms a heavier one. Mass is lost and a huge amount of energy is released (even energy amount is grater than the energy released in nuclear fission). Solar energy is a form of fusion energy. When two isotopes of hydrogen combine at very high temperatures, fusion occurs. The fusion of four protons to form a helium nucleus, two positrons (and two neutrinos) generates 24.7 MeV of energy. Nuclear Fission and Nuclear Fusion
Most of the energy radiated from the surface of the sun is produced by the fusion of protons to form helium atoms within its core.
Ex: hydrogen bomb
Properties of Nuclear Fission and Nuclear Fusion
- In the nuclear fission the splitting of a heavy nucleus into lighter nuclei.
- It is a chain reaction process.
- There is High temperature is not essential (Even Takes place at room temperature).
- Fission process is a controlled process and energy released can be used for peaceful purposes.
- It produced the large number of radioisotopes and large amount of nuclear waste.
- In nuclear fusion two or more lighter nuclei combine to form a heavy nucleus.
- The nuclear fusion not a chain reaction process.
- It required high temperature (106 oC).
- Fusion process is very difficult to be carried out in a controlled manner.
- In this process there is no nuclear waste is left.