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Essay on Atomic Structure, Moles and Periodicity

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Atomic structure, Moles and Periodicity

The Periodic Table is guidance or map to access different elements specific information, such as: atomic mass, isotopic richness, nuclear spins, electronic configuration and the position of elements belong to which group and period in table. Over the past decades there were many Scientifics which help to improvement of Periodic table but few of them made the most influence and contribution on Periodic table such as : Johann Dobereiner ,John Newlands , Dmitri Mendeleev and Henry Moseley.
Law of Triads
The development of Periodic table begins with the German chemist Johann Dobreeiner. He collected similar elements together. His triads were groups of three similar elements for example: Calcium,
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He continued his way and put forward the elements in order of increasing atomic mass and wherever he found a interval, simply assumed that this elements had not discovered yet. His way helped him to work out the atomic mass of undiscovered elements and predict their properties which the later on the new elements discovered it could go to the right place in his table. He put the elements in order of relative atomic mass and this gave a problem. For example: Iodine with lower atomic mass was after Tellurium in table and that breaking his rules.
Modern Periodic table
Henry Moseley came and put the elements in order of increasing atomic number. Actually Mendeelv was right to put Iodine after Tellurium but he did not know why is like this, but in Henry Moseley way iodine has higher atomic number than tellurium so iodine must be after tellurium in table.
In the modern periodic table vertical column called Group. There are 8 groups in periodic table which some of groups have names as well for example group seven named as Halogens or group eight (0) named as Noble gases. Groups often show an increase or decrease in similar properties. Elements in each group contain of same electron configuration in the outermost shell. A horizontal row called period, and they numbered from top to downwards 1-7. The periods consist of elements with the same
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