Question

$Al{H}_3$ is:

• A. pyramidal
• B. trigonal planar
• C. linear
• D. tetrahedral

Answer 1

Answer: (B)

$Al$ has $3$ valence electrons. Each of the hydrogens have $1$ valence electron. Thus, they complete their octet by mutually sharing their electrons. After sharing their electrons, Hydrogen's octet is fulfilled, but Aluminium's octet is not complete.

We can also see from the image that $Al{H}_3$ is trigonal planar in structure. Each of the bond angle is ${120}^o$. The bonds are equally spaced from each other too.

Option $B$ is the correct answer.