Question

What are the interhalogen compounds formed? What general compositions can be assigned to them?

Answer 1

An attempt to this question can be made by forming compounds by the reaction between two distinct halogen molecules. Halogens have the property of expanding their octet( except fluorine) and hence form a number of compounds with different valencies each time. So, write down all these compounds and then form a concise idea about their properties.

Complete step by step solution:
An interhalogen compound is a molecule which contains more than one different halogen atom only and not any other atoms from a different group. Most interhalogen compounds are found to form binary compounds i.e. having two distinct elements only.
These compounds are formed by direct combination between the halogens or by the action on a lower halogen i.e. the element above them in the 17th group.
As the elements of the 17th group have 7 electrons in the valence shell, they are often seen expanding their octet leading to multiple oxidation states. Thus, the general composition assigned to them can be as follows:
- $XY$
- $X{{Y}_{3}}$
- $X{{Y}_{5}}$
- $X{{Y}_{7}}$
Where,
X is more electronegative halogen than Y.

Note: Halogen atoms often expand their octet by exciting the pair of electrons to shift to higher energy orbital i.e. the corresponding d orbital. This helps in the element to show multiple oxidation states as they can now have more than 1 one bond pair. However, octet expansion in elements chlorine and below it. This is because fluorine does not have a d orbital. Due to this, it is unable to expand its octet. Hence it shows only one oxidation state of -1.