e                            e                             e    -                    -                             -      ...
The smallest part of an element that can exist. It                                                  consists of a nucleus ...
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-                           e                   +                       P             NucleusA nucleus is made up of two t...
Models of the Atom        Experimental data have been the impetus behind the creation and        dismissal of physical mod...
133                    51 sb              235        92U o n1                                    99                       ...
A nuclear reactor works on the                                                principle of steadily sustained             ...
Fission and Fusion Processes         Nuclear energy can be released in two different ways: by fission         (splitting) ...
If fusion energy does become practicable, it offersthe following advantages: (1) a limitless source offuel, deuterium from...
e        e         ee       8+    e   8n             e    e            e
Atoms and the nucleus sample
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Atoms and the nucleus sample

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Atoms and the nucleus sample

  1. 1. e e e - - - - - + + ++ + + + - - + -e- e e - - e e e e + P e 8+ e 8n e Nucleus e e © PRADIP. Asia Engl. School., Ahm.
  2. 2. The smallest part of an element that can exist. It consists of a nucleus of protons and neutrons, surrounded by orbiting electrons. e Every single thing you can see, hear, feel, smell, and - e - taste is made from microscopic particles. These - - particles are called atoms, and it would take millions + ++ + of them just to cover a full-stop. An atom is itself - - made up of even smaller particles. In the center of - - e e each atom there is a nucleus made up of protons and neutrons. Particles called electrons whiz around this e e nucleus in different shell(layers). Protons and - e e neutrons are much heavier than the electrons, so the e - - nucleus makes up most of an atom’s mass. Some - e 8+ substances, such as water, are made up of - 8n e molecules. These consist of several kinds of atoms e - - -e joined together in a group. Other substances, such as iron, have just one kind of atom.© PRADIP. Asia Engl. School., Ahm.
  3. 3. - e + + + + - e © PRADIP. Asia Engl. School., Ahm.The nucleus of every atom contains two types of particleprotons and neutrons. The number of protons gives theatomic number. Protons have a positive electriccharge, while neutrons have none. The electrons that spinaround the nucleus, like planets orbiting the sun, have anegative charge. But electrons are not solid balls, they arebundles of energy that move almost as fast as light. Thereare always the same number of electrons and protons inan atom.
  4. 4. - e + P NucleusA nucleus is made up of two types of particles, neutronswhich do not carry any charge; and protons which carry apositive charge exactly equal in magnitude to that of anelectron; i.e. 1.6 * 10-19 coulomb. Protons and neutrons havesimilar masses, but neutron is slightly heavier; both of thembeing much more massive than electrons. Neutron is 1838.65times more massive than an electron, proton is 1836.12 timesmore than electron. The simplest nucleus is that of an atomof ordinary hydrogen and consists of only a single proton.Both protons and neutrons are commonly known asnucleons. © PRADIP. Asia Engl. School., Ahm.
  5. 5. Models of the Atom Experimental data have been the impetus behind the creation and dismissal of physical models of the atom. Rutherford’s model, in which electrons move around a tightly packed, positively charged nucleus, successfully explained the results of scattering experiments, but was unable to explain discrete atomic emission—that is, why atoms emit only certain wavelengths of light. Bohr began with Rutherford’s model, but then postulated further that electrons can move only in certain quantized orbits; this model was able to explain certain qualities of discrete emission for hydrogen, but failed for other elements. Schrödinger’s model, in which an electron is described not in terms of definite paths but in terms of the likelihood of finding the electron in a particular region, can explain certain qualities of emission spectra for all elements; however, further refinements of the model, made throughout the 20th century, have been needed to explain further spectral phenomena. © Microsoft Corporation. All Rights Reserved. "Models of the Atom",Microsoft® Encarta® Encyclopedia 2001. © 1993-2000 Microsoft Corporation. All rights reserved.
  6. 6. 133 51 sb 235 92U o n1 99 41 NbWhen a 92 U nucleus is bombarded with a neutron, it absorbs theneutron and then breaks up into two roughly equal nuclei. Thisprocess is called the nuclear fission. © PRADIP. Asia Engl. School., Ahm.
  7. 7. A nuclear reactor works on the principle of steadily sustained nuclear chain reaction. It uses Y C fissile nuclei like 92 U235 and Pu239 .Use of appropriate moderator coolant and control F F F rods are essential to the proper design of a reactor using some specific fissile material as fuel X M M M M M gives the scheme to a reactor using slow neutrons. The C coolant flowing in through X carries away the energy generated in the form of heat R = Regulating rods F = Nuclear fuel through Y. C = Coolants, M = Moderators© PRADIP. Asia Engl. School., Ahm.
  8. 8. Fission and Fusion Processes Nuclear energy can be released in two different ways: by fission (splitting) of a heavy nucleus, or by fusion (combining) of two light nuclei. In both cases energy is released because the products have a higher binding energy than the reactants. Fusion reactions are difficult to maintain because the nuclei repel each other, but, unlike fission reactions, fusion reactions create far less radioactivity. © Microsoft Corporation. All Rights Reserved. "Fission and Fusion Processes",Microsoft® Encarta® Encyclopedia 2001. © 1993-2000 Microsoft Corporation. All rights reserved.
  9. 9. If fusion energy does become practicable, it offersthe following advantages: (1) a limitless source offuel, deuterium from the ocean; (2) no possibility ofa reactor accident, as the amount of fuel in thesystem is very small; and (3) waste products muchless radioactive and simpler to handle than thosefrom fission systems. "Nuclear Energy",Microsoft® Encarta® Encyclopedia 2001. © 1993-2000 Microsoft Corporation. All rights reserved.
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