Question

write two acheivment of mendelev periodic tabel

Answer 1

Acheivment of Mendeleev's periodic table:
1. When noble gases were discovered ,they could be placed in a new group without disrupting the existing order.
2. Mendeleev left some places in his table nd mentioned them as a plus point.
He predicted the existence of some elements tht had not been discovered at that time and named them by prefixing a Sanskrit numerical.
Later on,
scandium took the place of eka-boron
gallium took the place of eka-aluminim
germanium took the place of eka-silicon.

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Answer 2

1)To give the proper place in the periodic table,atomic masses of some elements were revised in accordance with their properties .for example,the previously determined atomic mass of beryllium,14.09,was changed to the correct value 9.4, and beryllium was placed before boron.

2) Mendeleev jad kept some vacant places in the periodic table for elements that were yet to be discovered.Three of these unknown elements were given the names eka-boron,eka-aluminiun ,& eka-silicon from the known neighbours and their atomic masses were indicated as 44,68,72, respectively.Their properties were also predicted.Later on these elements were discovered subsequently and we're named as scandium (SC) ,Gallium (GA) & germanium (Ge) respectively.The properties of these elements matched well with those predicted by Mendeleev.Due to this success all were convinced about the importance of Mendeleev's periodic table.

3)When Nobel gases such as helium,neon,and argon,were discovered , Mendeleev created the 'zero group's without distributing the original periodic table in which the Nobel gases were placed very well.


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