AlH3 Lewis structure

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AlH3 Lewis Structure
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.


Here’s how you can easily draw the AlH3 Lewis structure step by step:

#1 Draw a rough skeleton structure
#2 Mention lone pairs on the atoms
#3 If needed, mention formal charges on the atoms

Now, let’s take a closer look at each step mentioned above.

#1 Draw a rough skeleton structure

  • First, determine the total number of valence electrons
Periodic table

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

  • 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
AlH3 Lewis Structure (Step 1)
Rough sketch drawn, and got the stable Lewis structure of AlH3

#2 Mention lone pairs on the atoms

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.

In the above structure, you can see that the central atom (aluminum) forms an octet. And the outside atoms (hydrogens) also form a duet. Hence, the octet rule and duet rule are satisfied.

Therefore, this structure is the stable Lewis structure of AlH3.

Next: SbF3 Lewis structure

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