What makes h2o bent

Of course, the drawback of this is that it becomes more and more difficult to extract true chemical understanding from the numbers. Although it should also be said that you cannot extract any true chemical understanding from the VSEPR model. Because the Hamiltonian of the water molecule is invariant upon rotation, this means that indeed, any orientation of the water molecule is equally likely.

However, this only refers to the orientation of the water molecule as a whole. It does not say anything about the internal degrees of freedom, such as the bond angle. In the absence of any external force, the molecule is free to bend in whichever direction it likes, and most water molecules indeed do do this as they float through space or swim in a lake. But it will always be bent. This is quite similar to your argument. In the case of water, let's set the oxygen nucleus to be at the origin.

Because it can point either up or down, the expectation value of the hydrogen nucleus position along the up-down axis would be exactly level with the oxygen atom, i. In fact, don't stop there: it can point to the left or the right, and to the front or the back.

Does that mean it's actually there, though? You're confusing an expectation value with a genuine eigenstate which is what a resonance structure is. In exactly the same way, if you ever were to measure the properties of water and bear in mind that practically every interaction with a water molecule is, in effect, a measurement , we would find that it is indeed always bent. Lewis structures are dots around atoms on 2-dimensional paper.

Although H-O-H is planar, when you throw in the lone pairs, you have to think three-dimensionally. How would oxygen be hybridized, in readiness to accept two incoming hydrogens, each with an electron? Oxygen could hybridize as sp2p, with degree angles between bonds to hydrogen and a 90 degree angle between the p2 lone pair and the sp2 lone pair.

Or as sp3, with degrees between all the bonds. In water, we have I just can't decide which is the more powerful force; perhaps the water molecule can't either, so it just compromises. In this sense it can be seen as simple example of symmetry breaking its however not a simple first order Jahn-Teller distortion. Nobody says they exist "on the same side of the atom". In the picture showing Lewis structures of waters, the lone pairs are shown on opposite sides in the left panel , and on the same side on the right.

These two structures are identical. A Lewis structure does not make a statement about the geometry of a molecule. If you look at a 3D model of water where the lone pairs are shown according to sp3-hybridization in the valence bond view of things, it depends on the orientation of the molecule whether it looks like "on opposite sides" or "on the same side" the elongated shape - bunny ears - of the lone pairs is exaggerated; they should add up to a roughly spherical electron density.

In the molecular orbital view where the molecular orbitals share the symmetry of the molecule the two lone pairs have distinct shapes each panel shows one lone pair, orientation of the molecule distinct from figure above.

This was calculated using molcalc. As these two molecular orbitals are of similar energy, you could make linear combinations of them to arrive at orbitals similar to the valence bond picture. So what is the real picture?

Looking at hydrogen bond geometries, either one describes the directions from which hydrogen acceptors on other molecules would be located, so both models are consistent with experimental data.

There are eight valence electrons on the oxygen that have similar energies then there is a gap and two electrons very close to oxygen core follow. These eight electrons form four spin-pairs and those point in directions that more or less minimise the repulsion.

Now the two protons are connected with two of those "electron pairs" and two are "alone". Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. Why is the molecular structure of water bent? Ask Question. Nitrogen atom does not have an octet because the whole molecule is short an electron. This electron deficient feature of the molecule make is very reactive because it will try to react with some other molecule to complete the octet.

Elmhurst College. Lewis Diagrams. Trigonal Planar. Trigonal Pyrimid. Chemistry Department. Virtual ChemBook. Bent Molecular Geometry Water: Chime in new window An example of bent molecular geometry that results from tetrahedral electron pair geometry is H 2 O. Ozone: Chime in new window In this example, O 3 , the Lewis diagram shows O at the center with one lone electron pair and two other oxygen atoms attached. Nitrogen Dioxide: Chime in new window In this example, NO 2 , the Lewis diagram shows nitrogen at the center with one lone electron.

Nitrogen dioxide is a main component of photochemical smog air pollution. Polarity, in turn, gives rise to hydrogen bonding. Ice thus floats, forming an insulating blanket atop lakes and other bodies of water. This prevents them from freezing solid, killing all life within those bodies. All well and good. What is an unbonded pair? The oxygen atom center or nucleus ordinarily contains eight protons plus eight neutrons.