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Classification Of Elements And Periodicity In Properties

Question
CBSEENCH11005548
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What is the basic difference in approach between the Mendeleev’s Periodic Law and the Modern Periodic Law?

Solution

Mendeleev periodic law states that the physical & chemical properties of the elements are a periodic function of their atomic masses. In his periodic table, the elements are arranged in vertical rows called groups & horizontal rows are known as periods.There are nine groups & seven periods. He arranged only 60 elements in periodic table.

 An English physicist Moseley, in 1913 gave modern periodic law which states that the physical & chemical properties of the elements are the periodic function of their atomic number.This law becomes the base of modern periodic law.In the modern periodic table, there are 18 groups & 7 periods.

Some More Questions From Classification of Elements and Periodicity in Properties Chapter

What is the number of groups in: (i) p-block  (ii) d-block?

How many elements are present in:
(i) second period    
(ii) fourth period    
(iii) sixth period?

What is the name given to the s-block elements?

To which block the element with outer electronic configuration 4s23d10 belongs?

Why are there 10 elements in each series of d-block?

In terms of electronic configuration,
what is common in a given period and group?

Give the general electronic configuration of
(i) Transition elements     (ii) Inner transition elements.

Name the group and period to which an element with Z = 15 belongs ?

What are the advantages of periodic classification of elements?

In the modern periodic table, the period indicates the value of:
(a) atomic number
(b) atomic mass
(c) principal quantum number
(d) azimuthal quantum number.

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