By now, you know a lot about the group 17 elements. Do you remember what they are commonly called as? Yes! You are right! It’s halogens. So, what are we going to read about today? In this chapter, we will cover the concept of oxoacids of these elements, halogens. It is an important chapter as these oxoacids are very important compounds. Before we begin, let us have a brief recap of what we know about these group 17 elements.
Group 17 Elements: Halogens
Group 17 elements are fluorine, chlorine, bromine, iodine, and astatine from the top to the bottom of the group. We know them by “halogens” because they are salt producers. The members of this group are highly similar to each other. They exhibit a regular pattern in the physical and chemical properties. Did you know that astatine is the only radioactive element in the group? All of these elements have seven electrons in their valence shell. Their electronic configuration is ns2 np5
We can see that they are one electron less from the nearest noble gas or octet configuration. These elements have a small size because of their effective nuclear charge. Hence, these do not possess the tendency to lose electrons. As a matter of fact, they gain an electron easily and complete their octet configuration. Halogens produce several oxoacids. These are nothing but the acids containing oxygen in the acidic group.
Oxoacids of Halogens
You may ask, what are oxoacids? An oxoacid is a compound having hydrogen, oxygen, and no less than one other element. These do not have any lesser than one hydrogen molecule bound to oxygen. This hydrogen is capable of separating into the H+ cation and the anion of the acid.
The fluorine atom is extremely small and thus, it is highly electronegative. Therefore, it can form a single oxoacid, HOF which is fluoric(I) acid or hypofluorous acid. The other elements of the halogen family produce several oxoacids.
We cannot isolate them in the pure state. They are stable in aqueous solution. They are also very stable in their salt forms. Halogens generally form four series of oxoacids namely hypohalous acids (+1 oxidation state), halous acids (+3 oxidation state), halic acids (+5 oxidation state) and perhalic acids (+7 oxidation state).
Structures of the Oxoacids of Halogens
We can see that the focal halogen molecule is sp3 hybridised in these oxoacids. We can find an X-OH bond in each oxoacid. In the majority of these oxoacids, “X = O” bonds are available. Hypohalous acids incorporate hypofluorous acid, hypochlorous acid, hypobromous acid and hypoiodous acid. The halogen has the oxidation condition of +1 in hypohalous acids.
Some More Examples
Chlorine is capable of forming four types of oxoacids. They are HOCl (hypochlorous acid), HOClO (chlorous acid), HOClO2(chloric acid) and lastly HOClO3 (perchloric acid). Bromine forms HOBr (hypobromous acid), HOBrO2(bromic acid) and HOBrO3 (perbromic acid). Iodine forms HOI (hypoiodous acid), HOIO2 (iodic acid) and HOIO3 (periodic acid).
The central atom in the oxoacids is sp3 hybridized. Every oxoacid has essentially one X-OH bond. Whereas most oxoacids have X=O bonds present in them.
Solved Example for You
Q: Is hydrochloric acid an oxoacid?
Ans: No. Hydrochloric acid is a hydro acid.