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Modern Periodic Law:

The scientific world did not know anything about the interior of the atom when Mendeleev put forth the periodic table. After the discovery of electron, scientists started exploring the relation between the electron number of an atom and the atomic number. The atomic number in Mendeleev’s periodic table only indicated the serial number of the element.
 In 1913 A.D. the English scientist Henry Moseley demonstrated, with the help of the experiments done using X-ray tube that the atomic number (Z) of an element corresponds to the positive charge on the nucleus or the number of the protons in the nucleus of the atom of that element. This revealed that ‘atomic number’ is a more fundamental property of an element than its atomic mass. Accordingly the statement of the modern periodic law was stated as follows:
Properties of elements are a periodic function of their atomic numbers.

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26 April 2020 at 22:44