Oxoacids of halogen
The oxoacids of halogens are listed in the given table.
Halic (I) acid
Halic (III) acid
Halic (V) acid
Halic (VII) acid
The structures of oxoacids of chlorine are as follows:
Since fluorine has high electronegativity and small size, it forms only one oxoacid − HOF (hypofluorous acid).
Most of the oxoacids are not stable in pure state. They are stable only in aqueous solutions or in the form of their salts.
Two different halogens react with each other to form interhalogen compounds.
General composition −
X = Halogen of larger size
= Halogen of smaller size
X is more electropositive than .
As the ratio between radii of X and increases, the number of atoms per molecule also increases.
By the direct combination of halogens or by the action of halogen on lower interhalogen compounds
Some properties of interhalogen compounds are listed in the given table.
Physical state and colour
Pale brown gas
Very unstable, detected spectroscopically
Gas; at room temperature existence as solid is known
Ruby red solid (α-form)
Grown red solid (β-form)
Yellow green liquid
Colourless gas, but solid below 77 K
All are covalent in nature.
All are diamagnetic in nature.
Volatile solids or liquids at 298 K (Exception: ClF is a gas)
Physical properties are intermediate between those of constituent halogens. (Exception: m.p and b.p are a little higher than expected)
More reactive than halogens (except F)
Reason − bond in interhalogens is weaker than X − X bond in halogens. (Except F − F bond)
Give halide ion derived from smaller halogen; and a hypohalite (when ), halite (when ), halate (when ), and perhalate (when) anion derived from the larger halogen
Can be explained on the basis of VSEPR theory
It has bent T-shape.
The central Br atom has seven electrons in the valence shell.
Three of these will form electron pair bonds with three F atoms, leaving behind four electrons.
Thus, there are three bond pairs and two lone pairs.
According to VSEPR theory, lone pair-lone pair and lone pair-bond pair repulsions are greater than bond pair-bond pair repulsions.
Hence, to minimise these lone pair-lone pair and lone pair-bond pair repulsions, the BrF3 molecule acquires the shape of slightly bent ‘T’.
The given table lists the inter-halogen compounds with their structures.