Page 148 - Chemistry ICSE Class IX
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136 ICSE Chemistry – 9
Nature of Oxides
The elements at the beginning of a period form basic oxides. The elements
at the end of a period form acidic oxides. Thus, the basic nature of oxides
of the elements in a period decreases in going from left to right. For
example, sodium forms a basic oxide, while sulphur and phosphorus form
acidic oxides.
3rd period Na Mg Al Si P S Cl
sodium forms basic oxides these elements form acidic oxides
—— Oxides become more acidic in this direction o
Uses of Modern Periodic Table
What are the uses of modern periodic table
Some of the uses of the periodic table are:
The modern periodic table has made the study of elements and their
compounds more systematic and easier by correlating them with the
electronic con guration of the elements.
The position/location of an element in the periodic table provides the
following information:
Atomic number of the element.
Electronic con guration of the element.
Number of valence electrons in an atom of the element.
Valency of the element.
Properties of the element — whether metallic or nonmetallic.
The nature of the chemical bond, formulae of the compounds formed
and nature of the chemical compounds can be predicted from the
position of the reacting elements in the periodic table.
EXAMPLE 5.3. A section of the periodic table is shown below:
1 0
H 2 3 4 5 6 7 He
A B
C D
Out of A, B, C and D, which is,
(a) the most metallic element,
(b) the most nonmetallic element,
(c) the smallest atom?
Solution: (a) The metallic character increases while going from top to bottom in a
group. In a period, the metallic character decreases while going from left to right,
i.e.,
So, the most metallic element should occur at the bottom of group at the extreme
left. Thus, C is the most metallic in nature.
