(a) Why did Mendeleev have gaps in his periodic table? (b) State any three limitations of Mendeleev’s classification. (c) How does electronic configurations of atoms change in a period with increase in atomic number?

it was only valid till calcium....he did not gave fixed place to hydrogen.


Mendeleevs kept gaps for the undiscovered elements he also named them as eka in sanskrit
he did not give correct position for hydrogen because it can be placed on both 17th and 1st group
he did not give space for isomers which was introduced later
as the atomic no did not increase in regular manner it was not possible to predict how many elements can be introduced between 2 elements