Q6 of 28 Page 28

Write short notes.

Mendeleev’s periodic law.

Mendeleev stated a periodic law. The law states that “Properties of elements are periodic function of their atomic masses.”


⇒ Mendeleev arranged the elements according to their properties and in order of increasing atomic weights.


⇒ In the Mendeleev’s periodic table, vertical columns are called groups and horizontal rows are called periods.


⇒ Atomic masses of some elements were rediscovered so as to give them proper place in the periodic table.


⇒ Mendeleev kept vacant places in the periodic table for elements not discovered till then.


More from this chapter

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4

Write down the electronic configuration of the following elements from the given atomic numbers. Answer the following question with explanation.

6C, 3Li, 9F, 7N, 8O


Which of the above elements has the highest nonmetallic character?

 5

Write the name and symbol of the element from the description.

a. The atom having the smallest size.


b. The atom having the smallest atomic mass.


c. The most electronegative atom.


d. The noble gas with the smallest atomic radius.


e. The most reactive nonmetal.

 6

Write short notes.

Structure of the modern periodic table.

 6

Write short notes.

Position of isotopes in the Mendeleev’s and the modern periodic table.