AlH3 Lewis structure

AlH₃ (aluminum hydride) has one aluminum atom and three hydrogen atoms.

In AlH₃ Lewis structure, there are three single bonds around the aluminum atom, with three hydrogen atoms attached to it, and none of the atoms has a lone pair.

Alternative method: Lewis structure of AlH₃

Rough sketch

• First, determine the total number of valence electrons

In the periodic table, aluminum lies in group 13, and hydrogen lies in group 1.

Hence, aluminum has three valence electrons and hydrogen has one valence electron.

Since AlH₃ has one aluminum atom and three hydrogen atoms, so…

Valence electrons of one aluminum atom = 3 × 1 = 3
Valence electrons of three hydrogen atoms = 1 × 3 = 3

And the total valence electrons = 3 + 3 = 6

Learn how to find: Aluminum valence electrons and Hydrogen valence electrons

• Second, find the total electron pairs

We have a total of 6 valence electrons. And when we divide this value by two, we get the value of total electron pairs.

Total electron pairs = total valence electrons ÷ 2

So the total electron pairs = 6 ÷ 2 = 3

• Third, determine the central atom

Here hydrogen can not be the central atom. Because the central atom is bonded with at least two other atoms, and hydrogen has only one electron in its last shell, so it can not make more than one bond.

Hence, here we have to assume that the central atom is aluminum.

Therefore, place aluminum in the center and hydrogens on either side.

• And finally, draw the rough sketch

Lone pair

Here, we have a total of 6 electron pairs. And three Al — H bonds are already marked. So we do not have to mark any electron pair as a lone pair on the sketch.

Final structure

The final structure of AlH₃ features a central aluminum atom connected to three hydrogen atoms through single covalent bonds. In this arrangement, the aluminum atom serves as an exception to the octet rule, possessing an incomplete valence shell with only six electrons across three bonding pairs. Each hydrogen atom reaches its stable duet state through its single shared bond. This configuration is the most stable because it results in formal charges of zero for all atoms involved, representing the most energetically favorable state for the molecule. Accordingly, this specific electronic distribution serves as the definitive and most accurate Lewis representation of aluminum hydride.

Next: SbF₃ Lewis structure

External video

• How to Draw the Lewis Structure for AlH3: Aluminum Hydride – YouTube • Wayne Breslyn

External links

• https://lambdageeks.com/alh3-lewis-structure/
• https://www.answers.com/Q/What_is_the_Lewis_structure_of_AlH3
• https://oneclass.com/question/7330324-lewis-structure-for-alh3.en.html
• https://www.chegg.com/homework-help/questions-and-answers/part-b-alh3-draw-lewis-structure-molecule-include-lone-pairs-electrons-resonance-structure-q48078103