Give any 5 advantages and limitations of Mendeleev's periodic table and explain each of them?
advantages of mendeleev`s periodic table-
1. mendeleev`s periodic table was the base for modern periodic table.
2. medeleev left spaces in his periodic table for the elements which were unknown at that time.
3. when the elements unknown at that time were found then they were placed in the gaps without disturbing his periodic table.
4. with his periodic table he could predict the elements which were not known at that time.
5. when noble gases were found they were put separately at the corner in a new group without disturbing the existing table.
1. the elements were placed in wrong order of ATOMIC MASSES.
2.for example nickel and cobalt were placed in wrong order..
Advantages of Mendeleev's periodic table :
- Arranged 63 elements in a systematic order according to their increasing atomic masses and formula of their oxides and hydrides.
- He left gaps for the undiscovered elements.
- He correctly predicted the properties of undiscovered elements .e.g. scandium, germanium , gallium etc.
- Noble gases got a seperate group without disturbing the table.
- As the elements were classified into groups, it proved very useful in studying and remembering the properties of a large no. of elements in systematic way.
Disadvantages of Mendeleev's periodic table:
- Position of hydrogen was not justified.
- There was no space left for isotopes (elements having same atomic number but different atomic masses) in his table.
- Some elements having higher atomic masses were placed before those having lower atomic masses. ( Co with higher atomic mass was placed before Ni having lower atomic mass)
- Two similar elements like Cu and Hg were grouped differently.
- The position for actinides and lanthanides were not included in this table.
1) He could classify all the 63 elements discovered at that time on the basis of similarity in properties.
2) He left gaps for the elements to be discovered.
3) He predicated the properties of the undiscovered elements which were same as predicated.
4) It helped in correction of at.weight of certain elements on the basis of their position in the Periodic Table.
1) Even the elements were placed in order of incerasing order of atomic masses , incerasing order could not be maintained in all cases.(Cobalt 58.93 nickle 58.71)
2) Mendeleev's Periodic Table did not provide place for noble gases which were discovered later.
3) There was no proper place for isotopes,
4) Hydrogen did not had a proper place .