Advantages and disadvantages of Mendeleev' periodic table???????
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Limitations are :
Position of hydrogen : Hydrogen is placed in Group IA. However, it actually resembles the elements of Group-IA (alkali metals ) as well as the elements of Group VII-A (halogens ). Thus, the position of hydrogen in the periodic table is not clear.
Position of isotopes : On the basis of atomic weight , various isotopes of the same elements should be assigned different places in the periodic table. Mendeleev could not provide separate places for isotopes.
Position of lanthanides and actinides : Fourteen elements following Lanthanum(known as lanthanides orrare earths) and the fourteen elements following Actinium (known as actinides or transuranic elements ) have not been provided separate and proper places in the Mendellev's table, rather they have been placed in two rows at the bottom of the table.
Disimilar elements placed together : Noble metals like Cu, Ag and Au are placed along with chemically dissimilar alkali metals in Group I . Similarly, Mn possessing very few similarities with halogens have been placed in VII group.
Similar elements separated : In Mendeleev's periodic table, certain chemically similar elements such as copper and mercury ; gold and platinum have been placed in different groups.
Anomalous pairs : In the Mendeleev's Table based on atomic weight, the positions of certain pairs , e.g. Argon( at. wt = 39.94) and potassium ( at. wt = 39.1) : Cobalt( at wt =58.93 ) and nickel ( at wt = 58.71 ) ; Tellurium at wt = 127.60) and iodine (atomic weight = 126.90 ) would be reversed. In other words, certain pairs of elements are misfit in the periodic table, if atomic weight is the basis of classification.
Advantages
IT HAS WELL DEFINED GROUPS AND PERIODS WHICH WOULD TELL US ABOUT THE NATURE OF THE ATOMS IN A GROUP
IT IS CLASSIFIED IN A WELL DEFINED MANNER WHICH WILL HELP MORDERN PERIODIC TABLE
HE LEFT SPACES IN HIS PERIODIC TABLE TO FILL THE FUTURE DISCOVERED ELEMENTS WHICH WERE PREDICTED BY HIM
HE CORRECTED SOME OF THE DEFECT IN MASS NUMBERS
Hope this helps !!!!!!
Position of hydrogen : Hydrogen is placed in Group IA. However, it actually resembles the elements of Group-IA (alkali metals ) as well as the elements of Group VII-A (halogens ). Thus, the position of hydrogen in the periodic table is not clear.
Position of isotopes : On the basis of atomic weight , various isotopes of the same elements should be assigned different places in the periodic table. Mendeleev could not provide separate places for isotopes.
Position of lanthanides and actinides : Fourteen elements following Lanthanum(known as lanthanides orrare earths) and the fourteen elements following Actinium (known as actinides or transuranic elements ) have not been provided separate and proper places in the Mendellev's table, rather they have been placed in two rows at the bottom of the table.
Disimilar elements placed together : Noble metals like Cu, Ag and Au are placed along with chemically dissimilar alkali metals in Group I . Similarly, Mn possessing very few similarities with halogens have been placed in VII group.
Similar elements separated : In Mendeleev's periodic table, certain chemically similar elements such as copper and mercury ; gold and platinum have been placed in different groups.
Anomalous pairs : In the Mendeleev's Table based on atomic weight, the positions of certain pairs , e.g. Argon( at. wt = 39.94) and potassium ( at. wt = 39.1) : Cobalt( at wt =58.93 ) and nickel ( at wt = 58.71 ) ; Tellurium at wt = 127.60) and iodine (atomic weight = 126.90 ) would be reversed. In other words, certain pairs of elements are misfit in the periodic table, if atomic weight is the basis of classification.
Advantages
IT HAS WELL DEFINED GROUPS AND PERIODS WHICH WOULD TELL US ABOUT THE NATURE OF THE ATOMS IN A GROUP
IT IS CLASSIFIED IN A WELL DEFINED MANNER WHICH WILL HELP MORDERN PERIODIC TABLE
HE LEFT SPACES IN HIS PERIODIC TABLE TO FILL THE FUTURE DISCOVERED ELEMENTS WHICH WERE PREDICTED BY HIM
HE CORRECTED SOME OF THE DEFECT IN MASS NUMBERS
Hope this helps !!!!!!
3Bhumika:
thanks dear
Wlcmm
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advantages of mendeleef periodic table
Predicting some elements like eka silicon, eka boron, eka aluminium.
Correcting atomic weights
8 vertical groups
7 periods
each group divided into sub groups A, B
disadvantages
anomalous pair of elements
example tellurium (127.6 U), has more atomic weight than iodine (126 U) but tellurium is placed first
non separation of metals and non metals
Anamolous pair of elements
Predicting some elements like eka silicon, eka boron, eka aluminium.
Correcting atomic weights
8 vertical groups
7 periods
each group divided into sub groups A, B
disadvantages
anomalous pair of elements
example tellurium (127.6 U), has more atomic weight than iodine (126 U) but tellurium is placed first
non separation of metals and non metals
Anamolous pair of elements
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