Question

Which of the following species are hypervalent? 1. \[Cl{O_4}^ - \] 2. \[B{F_3}\] 3. \[S{O_4}^{2 - }\] 4. \[C{O_3}^{2 - }\]
A. 1. 2. 3
B. 1.3
C. 3.4
D. 1.2

Answer 1

Hint: Hypervalent compounds are those which contain more than eight electrons in their valence shell. That means in a molecule that center atom possess’ greater electron than its nearest inert gas. This is only possible when the central element possesses vacant d orbitals in its vacant shell.

Complete step by step answer:
In the case of chlorine, the valence shell is the third shell, which possesses a vacant d orbital. Due to this reason it can extend its covalency by increasing the unpaired electrons using vacant d-orbital. By this chlorine can show a higher oxidation state than its actual valency. This kind of nature is also shown in other elements like sulfur, iodine, bromine, phosphorus, etc.
From the given options, the ions with the central atom containing vacant d-orbital are the hypervalent species. Which are, \[Cl{O_4}^ - \],\[S{O_4}^{2 - }\]

So, the correct option is B.

Addition information:
There are some other kinds of compounds which are known as hypervalent compounds. These compounds possess a’ lower number of electrons than the octet in their valence shell. This is because of a lack of electrons in their valence shell to increase their covalency. For example, in the case of boron, the valence shell of boron possesses only three electrons by which it can form a bond with another three electrons therefore octet will not be fulfilled. This is also noticing in aluminum, beryllium, etc.

Note:
Hypervalent means which contains more than eight electrons in their valence shell. Hypo valent means compounds possess a lower number of electrons than the octate in their valence shell. This kind of abnormal behavior is only possible in covalent bonding, by sharing of the electron.