Using IUPAC nomenclature, give the name of BH3 and AlH3 and elaborate why that name is correct

[tex]BH_3[/tex] is a covalent compound as it is a compound formed between two non-metals. In this compound, boron and hydrogen shares electrons to form a bond.

The IUPAC nomenclature of covalent compound is given by some rules, which are:

The less electronegative element is written first. in the naming.
The more electronegative element is written then with a suffix at the end of it. The suffix used is '-ide'.
If the number atoms of an element is greater than 1, then prefixes are added which are 'mono' for 1 atom, 'di' for 2 atoms, 'tri' for 3 atoms and so on..

So, the name for [tex]BH_3[/tex] compound is boron trihydride.

[tex]AlH_3[/tex] is an ionic compound because aluminium element is a metal and hydrogen element is a non-metal and bond formed between a metal and a non-metal is always ionic bond.

The IUPAC nomenclature of ionic compounds is given by some rules, which are:

Positive ion (Cation) is written first. in the naming.
The negative ion (anion) is written next with a suffix at the end of the negative ion. The suffix written is '-ide'.

Hence, the IUPAC name of [tex]AlH_3[/tex] is aluminium hydride.