H2O Molecular Geometry, Lewis Structure, Shape and Bond Angles

As you know, I have explained about the molecular shape of CO2, SO2, SO3, SF4, and XeF4. Today, it’s time to remember about the molecular shape of H2O. As we know, it is the formula of water and also one of the most well-known chemical formulas. In this article, my young followers will get the information of H2O molecular geometry and H2O Lewis structure. So stay tuned and find the answers.

H2O Molecular Geometry

What is the electronic geometry of H2O?

To determine the molecular geometry for H2O, we need to look at the Lewis structure firs. There are two Hydrogens on the central oxygen, but very importantly there are also two pairs of electrons on the top and bottom of the oxygen at this Lewis structure. So, according to valence shell electron pair repulsion theory, those four things will spread out as far as possible, and that’s what’s going to give us our molecular geometry or our shape for H2O.

H2O Lewis Structure

H2O Lewis Structure

Molecule Shape of H2O

In order to visualize H2O shape, let’s look at it in three dimensions. So, here’s the water molecule we have. The pink one is the Oxygen, and the Hydrogens are the whites. The lone pair electrons there on top. So as we look at this, we can see it’s not a straight molecule, it has a bent shape, and that’s going to be the molecular geometry bent.Molecule Shape of H2O

One another method is to use the AX and Notation to figure out the geometry.axn

‘A’ that’s the central atom we are dealing with! In this case, the Oxygen ‘X’ is going to be the number of atoms attached to the oxygen. We have the two Hydrogens. So we are going to put it two here and ‘N’ – that’s the nonbonding electron pairs.ax2n

We have two pairs;H2O electron geometry

So, N is going to be two as well you could have memorized that A X2 N2 has a bent molecular geometry.

H2O Bond Angles

There is also an easy way available. Look it up on this table.

 

Formula Shape Bond Angles        
AX2 Linear 180
AX3 Trigonal planar 120
AX4 Tetrahedral 109.5
AX5 Triangular Bipyramidal 120, 90
AX6 Octahedral 90
AX2N Bent 120
AX2N2 Bent 109.5
AX3N Trigonal pyramidal 109.5

Here in the table, when we go down, we see AX2 and 3 and all the way down AX6, AX2N and there it is at the bottom – AX2N2, which has a bent molecular geometry and the bond angles are going to be 109.5 degrees.

So, using both the valence shell electron pair repulsion theory and using the table where we look at the AX and Notation, we figured out the molecular geometry for water. H2O is a three atom molecule with the angular shape.

I hope I was able to explain the H2O electron geometry in the easy but useful manner.  The geometry of molecules is not complicated to understand if you pay proper attention to the formulas. Yes, it is essential to be clear with some basic concepts, and there you go. You can crack any formula and even can explain others. Keep trying, keep learning, keep teaching!

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