Quarks, leptons and their antiparticles.Nuclear fusion is the main source of the sun’s energy.Nuclear fusion yields more energy than nuclear fission.A great amount of energy is released in nuclear fusion due to the greater binding energy of the daughter nucleus.Nuclear fusion is the joining of two light nuclei to form a heavy nucleus.Nuclear fission is used in nuclear power plants.A great amount of energy is released in nuclear fission due to the greater binding energy of the daughter nuclei.Nuclear fission is the splitting of a heavy nucleus into two lighter nuclei.Where E is energy in J, m is mass in kg, and c is the speed of light in m/s FYI Binding energy per nucleon = binding energy of nucleus / number of nucleons in nucleus.The nuclear binding energy of a nucleus is the amount of work required to separate the nucleons inside the nucleus.Mass defect can be explained by Einstein’s mass-energy equivalence: As energy required to break apart a nucleus, the sum of energy contained in the constituent nucleons is higher than that of the combined nucleus.The difference between the mass of an atom and the sum of mass of its constituent parts is called its mass defect.It is defined as one twelfth of the mass of a carbon-12 atom. The unified atomic mass unit (μ) is commonly used in nuclear physics. Artificial sources: radioactive waste from nuclear power plants, radioactive fallout from nuclear weapons, medical x-raysĪverage composition and exposure of background radiation.Natural sources: cosmic rays from space, radioactive rocks and soil, living organisms that have consumed radioactive substances in the food chain.Absorption characteristics of decay particlesĭifferent isotopes of a given element have the same atomic number (atomic number defines the type of element) but different mass numbers because they have different numbers of neutrons.īackground radiation comes from natural sources and artificial sources.See previous section (Radioactive decay). Its ionizing power is in the lowest among the three types of particles.Its penetration power is the highest among the three types of particles and can be blocked by several cm of lead.Its ionizing power is in the middle among the three types of particles.Its penetration power is in the middle among the three types of particles and can be blocked by a thin sheet of aluminum.Its ionizing power is the highest among the three types of particles.Ī beta particle is an electron or a positron.Its penetration power is the lowest among the three types of particles and can be blocked by a piece of paper or a few cm of air.Alpha particles, beta particles and gamma rays.Fundamental forces and their properties.If we plot the amount of radioactive nuclei which have not yet decayed with time, the resulting curve is called the decay curve and can be shown as the following.The radioactive half-life of a substance is the time it takes for half of its radioactive nuclei to decay.The activity of radioactive decay can be shown by half-lives.The daughter nucleus is energetically unstable.The product nucleus from a radioactive decay is called a daughter nucleus. Radioactive decay refers to the spontaneous random process by which particles or electromagnetic radiation is emitted from an unstable nucleus.The amount of energy absorbed or released can be calculated by the difference in energy (eV) between the two energy levels. Likewise, light is absorbed when the electrons within an atom jump from one atomic energy level to a higher energy level. When the electrons within an atom jump from one atomic energy level to a lower energy level, energy is released in the form of light. The existence of discrete energy levels called atomic energy levels can be supported by the emission spectra and the absorption spectra of atoms.These frequencies appear as spectral lines in the emission and absorption spectra. Therefore, only photons with frequencies which correspond to the differences between the atomic energy levels can be absorbed or released by an atom. The energy of a photon is dependent on its frequency.The amount of energy absorbed or released is equal to the difference between the discrete atomic energy levels and is also quantized. As an electron makes a jump from one energy level to another, energy is absorbed or released in the form of a photon.The electrons of an atom can occupy certain discrete atomic energy levels.Discrete energy and discrete energy levels.
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