Embibe Experts Solutions for Chapter: Periodic Classification of Elements, Exercise 1: Exercise

Which of the following elements have properties similar to that of eka boron?

The modern periodic table has been evolved through the early attempts of Dobereiner, Newland and Mendeleev. List one advantage and one limitation of all the three attempts.

What were the limitations of Newlands' law of octaves?

Can the following groups of elements be classified as Dobereiner’s triads?
a) $\mathrm{Na}, \mathrm{Si}, \mathrm{Cl}$    b) $\mathrm{Be}, \mathrm{Mg}, \mathrm{Ca}$
Give reason for your answer
(Atomic masses: $\mathrm{Be} 9; \mathrm{Na} 23; \mathrm{Mg} 24; \mathrm{Si} 28; \mathrm{Cl} 35.5; \mathrm{Ca} 40$)

Using Mendeleev's periodic table, predict the formula for the oxides of the following elements:

$\mathrm{K}, \mathrm{C}, \mathrm{Al}, \mathrm{Si}, \mathrm{Ba}$.

The atomic radii of the elements of second period are given below:

(a) Arrange the elements in the decreasing order of their atomic radii, keeping the element with the largest atomic radius first. 
(b) Find out whether the arrangement is in the pattern of a period or not? 
(c) From this data, infer how the atomic size of the elements changed as one goes from left to right in a period.

Describe how the number of valency electrons changes with group number, across the Periodic Table.

An element $\mathrm{X}$ from group $2$ reacts With element $\mathrm{Y}$ from group $16$ of the periodic table. 
(a) What is the formula of the compound formed?
(b) What is the nature of bond in the compound formed?