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| Atomic Nucleus |
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| It is the central core of the atom where the entire +ve charge and mass is concentrated. It is a tiny sphere of diameter ranging from 10-15m to 10-14m. A nucleus is made up of particles called neutrons and protons. A neutron does not carry any charge while a proton does (+e=1.6x10-19C). Neutron and proton are regarded as different charged states of the same particle called Nucleon. |
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| Atomic number is the number of protons present inside the nucleus and is also equal to the number of electrons. |
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| Mass number is the total number of protons and neutrons inside the nucleus. |
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| A nuclide is specific nucleus of an atom represented as |
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| ZXA where A is the Mass number |
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| Z is the atomic number |
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| X is the symbol of elements. |
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| Experiments reveal that volume of a nucleus is proportional to the mass number A. |
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| i.e., V a A |
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| 4/3p R3 a A |
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| R a (A) 1/3 |
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| or R = Ro A 1/3 |
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| (Where R is radius of nucleus assumed to be spherical) |
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| Ro = 1.1x 10-15 m an empirical constant |
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| \The atomic nucleus of different elements have different sizes. |
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| where m is average mass of a nucleon. |
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| or |
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| Putting m = 1.66 x 10-27 Kg, Ro = 1.1x10-15 m, we find |
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| (Rh0) r = 2.98 x 1017 Kg /m3 |
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| i.e., Nuclear density is same for all elements and is densely packed. |
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| Note that the sizes of nuclei are different but density of nuclear matter is same for all nuclei. However the value of nuclear density is far more greater than atomic density. |
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