Explain the comparison of Mendeleev and Modern periodic table?
Comparison of Mendeleev and Modern periodic table
|S.No.||Characteristic||Mendeleev Periodic Table||Modern Periodic Table|
|1.||Arrangement of elements||In Mendeleev's periodic table elements are arranged in increasing order of their atomic weight.||In the modern periodic table, elements are arranged according to their increasing atomic number.|
|2.||Position of isotopes (elements with the same atomic number but with different mass numbers)||In Mendeleev's periodic table isotopes of every element were given a different place||In the modern periodic table, isotopes were placed with the element itself.|
|3.||Number of elements||Mendeleev’s periodic table was for the arrangement of 63 elements known at that time.||The modern table accommodates all the 118 natural and synthetic elements.|
|4.||Uneven grouping of elements||In Mendeleev’s periodic table, coinage metals like copper, silver, and gold are grouped with very active alkali metals. Manganese metal was grouped with halogens in the seventh group.||This defect was rectified in the Modern periodic table.|
|5||Anomaly in Mendeleev's table|| In Mendeleev’s periodic table the element pairs, Argon-potassium, cobalt-nickel, tellurium-iodine, and thorium and protactinium, elements with higher atomic mass precede the element with lower atomic mass. |
It is the right place for them but is against Mendeleev’s periodic law.
|The modern periodic table rectifies the defects of Mendeleev’s periodic table.|
|6||Number of periods and groups||Mendeleev's periodic table was divided into 7 periods and 8 groups and each group is further subdivided into subgroups.||The modern periodic table is divided into 18 groups and 7 periods.|