Question

"Properties of the elements are the periodic functions of their atomic number"-
modern periodic law
The earliest attempt to classify the elements resulted in grouping the then known
elements as metals and nonmetals , later further classification were tried out as
our knowledge of elements and their properties increased,
We can observe gradual change in valency ,atomic size and metallic properties
across the period and down the group in the periodic table For example atomic
radii of the elements of the second period are given below.
Li
Be
B
С
N
0
152pm
111pm
88pm
77pm
74pm
66pm
() Atomic radii of the elements in the first group is given as follows:
K(231pm), Rb(244pm), Li(152pm), Na(186pm),Cs(262pm)
Arrange them in decreasing order
(ii) How can you calculate the valency of an element from its electronic
Configuration?
(iii)On which side of the periodic table do you find the non metals?
(iv)How do you think the tandency of loosing electron changes in a group?
(v) Name the elements that have two electrons in its outermost shell from the
above elements?​

Answer 1

Explanation:

i) Cs>Rb>K>Na>Li

ii) The valency of an element is determined by the number of valence electrons present in the outermost shell of its atom. The number of electrons lost or gained (or shared) by one atom of an element to achieve the nearest inert gas electron configuration, gives us the valency of the element.

iii) We find the non metals on the right side of the periodic table, that is P block.

iv) On moving down a group, the number of shells increases at each succeeding element. As a result, the valence electrons lies farther away from the nucleus. Therefore, the force of attraction between nucleus and the electrons decreases and tendency to lose electrons increases down the group.

v) Be, C