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Justify the given statement with suitable examples -"the properties of the elements are a periodic function of their atomic numbers"? |
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Answer» The case of periodicity in properties is the repetition of similar outer electronic configuration after certain regualr intervals. e.g., all the elements of 1st group (ALKALI metals) have similar outer electronic configuration. i.e., `ns^(1)`. `._(3)Li = 1s^(2).2s^(1)` `._(11)Na=1s^(2), 2s^(1), 2P^(6), 3s^(1)` `._(19)K=1s^(2), 2s^(2), 2p^(6), 3s^(2), 3p^(6), 4s^(1)` `._(37)Rb=1s^(2), 2s^(2), 2p^(6), 3s^(6), 3d^(10), 4s^(2), 4P^(6), 5s^(1)` `._(56)Cs=1s^(2), 2s^(2), 2p^(6), 3s^(2), 3p^(6), 3d^(1), 4s^(2), 4p^(6), 4d^(10), 5s^(2), 5p^(6), 6s^(1)` `._(87)Fr=1s^(2),2s^(2),2p^(6),3s^(2),3p^(6),3d^(10),4s^(2),4p^(6),4d^(10),4f^(14)` `5s^(2), 5p^(6), 5d^(10)6s^(2), 6p^(6), 7s^(1)` Therefore, due to similar outermost shell electronic configuration all alkali metals have similar properties. e.g., sodium and potassium both are soft and reactive metals. They all form unpositive ion by the LOSE of one electron. Similarly, all the elements of 17th group (halogens) have similar outermost shell electronic configuration, i.e., `ns^(2)np^(5)` and thus possess similar properties. `._(9)F=1s^(2) , 2s^(2), 2p^(5)` `._(17)Cl=1s^(2), 2s^(2), 2p^(6), 3s^(2), 3p^(5)` `._(35)Br=1s^(2), 2s^(2), 2p^(6), 3s^(2), 3p^(6), 3d^(10), 4s^(2), 4p^(6), 4d^(10), 5s^(2), 5p^(5)` `._(53)I= 1s^(2), 2s^(2), 2p^(6), 3s^(2), 3p^(6), 3d^(10), 4s^(2), 4p^(6), 4d^(10), 5s^(2), 5p^(5)` `._(85)At=1s^(2), 2s^(2), 2p^(6), 3s^(2), 3p^(6), 3d^(10), 4s^(2), 4p^(6), 4d^(10), 4f^(14), 5s^(2), 5p^(6), 5d^(10), 6s^(2), 6p^(5)` |
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