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Nuclear Chapters
Question | Answer |
---|---|
Isotopes | Same number of protons, different number of neutrons |
Isobars | Same number of nucleons, but different number of protons and neutrons |
Isotones | Equal number of neutrons |
Alpha decay | Z-2 A-4 Helium is emitted |
Negative Beta decay | A remains the same Z+1 Electron and anti neutrino is emitted |
Positive Beta decay | A remains the same Z-1 Positron and neutrino is emitted |
Gamma decay | No change in Z and A |
Mass defect of a nucleus | ∆m=([Zmp+(A-Z)mn]- M) ÷ Mass of nucleus, |
Binding energy | ∆m(in amu)×931/931.5 Mev |
Binding energy per nucleus | B.E÷A |
Nuclear radius | R=RoA^(1/3) Ro=1.2×10^(-15)m |
Nuclear density | 2×10^(17) kg/m³ Nuclear density is independent of atomic mass number |
Fission of U235 92 nucleus | 92U235 + 0n1 — 56Ba141 + 36Kr92 + 3 (0n1) + Q |
Uncontrolledchain reaction | Nuclear bomb |
Controlled chain reaction | Nuclear reactor |
Difference between radioactive decay and nuclear fission | Rate of decay cannot be controlled, but the rate of fission can be controlled Radioactive decay is spontaneous, but fission is not. The heavy nuclei is bombarded by neutrons. |
Moderator in a nuclear reactor | Slows down the neutron to thermal energies through eleastic collisions between it's nuclei and the fission neutrons. Thermal neutrons have high probability of fissioning U235 nucleus. Water is the best moderator. |
Control rods in a nuclear reactor | Rods of cadmium which are used to control the fission rate in the reactor.cadmium and boron are good absorbers of slow neutrons.hence they control the fission rate. |
Nuclear fusion reaction | 1H2 + 1H2 — 1H3 + 1H1 + 4.0 Mev |
Difficulties in Nuclear fusion | It is a very difficult process. Since, the nuclei to be fused are positive, they would repel one another strongly. They must be bought closer by high pressure but also with high kinetic energies. A temperature of 10^8 is required. |