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5. The Halogens and the Noble Gases eLearn.Punjab

4. An acid in which the oxidation state of the parent atom is lower than it
is in the___ ous acid is called hypo _____ ous acid and a salt of this acid is a
hypo _____ ite salt. For example, hypochlorous acid (HCIO).
5. The root of the name of the acid or the salt indicates the parent atom.

Table 5.4 shows the oxyacids of halogens (other than fluorine)
Table 5.4 Oxyacids of Halogens

Oxidation Formula of the oxyacids of General names of
state halogens
Oxyacids Salts of
of halogen Chlorine Bromine Iodine oxyacids
Hypohalous acid Hypo__ite
+1 HCIO HBrO HIO Halous acid ____ite
+3 ------ ------ Halic acid ____ ate
+5 HCIO2 HBrO3 Perhalic acid Per____
+7 HCIO3 HIO3 ate
HCIO4 HIO4, H5IO6

It is evident from the above given formulas of the oxy acids that
the halogen serves as a central atom to which one or more oxygen
atoms are covlently bonded. These bonds are polar in character due
to the electronegativity difference between halogen and oxygen.

The increase in the oxidation state of the halogen from +1 to + 7 is
accompanied by :
(a) an increase in the thermal stability of the acid
(b) the decrease in oxidizing power of the acid
(c) the increase in acidic strength of the acid

The more the number of oxygen atoms in the series of oxyacids of a halogen,
the greater is the thermal stability.

The acid strength increases with the increase in the number of oxygen atoms.
As the oxidation state of the halogen increases, the bonding electrons are
shifted away from the Hatom and the tendency of the molecule to lose a
proton increases. This accounts for the change of strength of oxyacids.
The oxyacids of halogens show their strength in the order given below:

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