Write the drawbacks in mendeleef's periodic table that led to its modification.
Write the drawbacks in mendeleef's periodic table that led to its modification.
The main drawbacks of Mendeleef's periodic table are
(i) Some elements having similar properties were laced in different roups whereas some elements having dissimilar properties were placed in the same group.
e.g., alkali metls such as Li, Na, K, etc, (IA group) are grouped toether with coinage metals such as Cu, Ag, Au (IB group) though) their properties are quite different. Chemically similar elements such as Cu, (IB group) and Hg (IIB group) have been placed in different groups.
(ii) Some elements with higher atomic weights ae placed before the elements with lower atomic weights in order to maintain the similar chemical nature fo elements.
i.e., 39.918Arand39.118K:58.927Coand58.728NI,etc.
(iii) Isotopes did not find any place in the periodic table. However, according to Mendeleedf's classification, these should be placed at different places in the periodic table.
(iv) Position of hydrogen in the periodic table is not fixed but is controversial.
(v) Position of elements of group VIII could not be made clear which have been arranged in three triads without any justification,
(vi) It could not explain the even end odd series in IV, V and VI long periods.
(vii) Lanthanides and actinides which were discovered later on have not been given proper positions in the main frame of periodic table,
The main drawbacks of Mendeleef's periodic table are
(i) Some elements having similar properties were laced in different roups whereas some elements having dissimilar properties were placed in the same group.
e.g., alkali metls such as Li, Na, K, etc, (IA group) are grouped toether with coinage metals such as Cu, Ag, Au (IB group) though) their properties are quite different. Chemically similar elements such as Cu, (IB group) and Hg (IIB group) have been placed in different groups.
(ii) Some elements with higher atomic weights ae placed before the elements with lower atomic weights in order to maintain the similar chemical nature fo elements.
i.e., 39.918Arand39.118K:58.927Coand58.728NI,etc.
(iii) Isotopes did not find any place in the periodic table. However, according to Mendeleedf's classification, these should be placed at different places in the periodic table.
(iv) Position of hydrogen in the periodic table is not fixed but is controversial.
(v) Position of elements of group VIII could not be made clear which have been arranged in three triads without any justification,
(vi) It could not explain the even end odd series in IV, V and VI long periods.
(vii) Lanthanides and actinides which were discovered later on have not been given proper positions in the main frame of periodic table,
