Why is the water molecule bent?

Question

It has always facinated me as to y it is bent...

Answer 1

The oxygen atom has four pairs of electrons about it (its own 6 valence electrons and the 2 electrons from the 2 hydrogens). In order to minimize electron pair repulsions, those electrons will attempt to get as far apart as possible, and the arrangement that allows this for four electron pairs is tetrahedral, where the angle between pairs is 109.5 degrees. Two of those corners of the tetrahedron are taken up by lone pairs, which force the hydrogens at the other two corners a little closer together (think of the range of motion of a string tied at one end and one tied at two ends; a lone pair of electrons takes up more room than a bonding pair) so water's angle is 106.5 degrees.

If there were no lone pairs present, water would be linear (like BeF2) but the lone pairs force a different geometry.

Answer 2

Ah. It's because of orbitals. The electrons of an atom can't be just anywhere, they fill special slots or shells, called orbitals. (Each orbital is equivalent to one line on the periodic table, btw) The inner orbital of an atom is spherical. Meaning the electrons can be found anywhere around the nucleus. When that's filled, with two electrons, the next orbital starts to fill up. You can kind of intuit that, as you add orbitals, each one has more energy than the last, and more energy twists things into more complicated shapes, the way a jump rope gets a lot of complicated waveforms if you really wave the end up and down, compared to just a simple slow twirl.So, the second orbital, which you can see from the period table holds the next 8 electrons, number 3 to number 10, is not spherical, but has the 8 electrons in 4 lobes ("suborbitals") arranged in a tetrahedron, equidistant around the outside of the sphere, with a little more than 100 degrees between any pair, so that any three form sort of a triangle below the center with the fourth pointed away from them, kind of like one of those 4 pointed gadgets the cops toss on the road to blow the crooks' tires in the movies. Since oxygen doesn't have 10 electrons, only 8, ther aren't 8 electrons in this orbital, only 6, meaning there are two vacancies in this orbital. Since electrons like to get as far away from each other as possible, you don't get 3 suborbitals with 2 electrons each and one with none, you get two with 2 electrons each and two with one each. That leaves room for one more electron in each of the two half empty suborbitals, which are arranged in that tetrahedral setup so that the angle between them is a little more than 90 degrees. That's where the hydrogens attach.

Answer 3

The water molecule is bent because there are two non-bonding electron pairs on the Oxygen. These two non-bonding electron pairs exert a repulsive force that bends the H2O molecule.

To give you a picture of what this means, in an H2O molecule, there are two Hydrogen molecules and two non-bonding electron pairs bonded to the Oxygen molecule, giving the Oxygen molecule an octet (8 electrons). Since the 3D structure of the H2O molecule is tetrahedral, the two non-bonding electron pairs will be next to each other and will repulse the other two Hydrogen molecules closer to each other.

I hope the explanation makes sense. It's hard to explain when I can't draw it. :]

Answer 4

The oxygen in h2o has 6 valence electrons. That means it has two lone pairs to bond with the hydrogen. When the hydrogen is bonded with the oxygen, the lone pairs 'push' the hydrogens down making it bent. This causes water to be polar.

For a picture of what I'm talking about go to this website: http://witcombe.sbc.edu/water/chemistrystructure.html

Answer 5

well, shapes of a molecule depends on types of bonding and how many electrons are left unpaired after the bonding. The electrons that are left unpaired would repel each other and it cause all these shapes.

If I am not mistaken, after oxygen paired with both hydrogens, there are 2 pairs of electrons with no molecules to bind to, so the repulsion causes the bent shape.

Answer 6

It is bent because the hydrogen atoms have less electronegativy than the oxygen atoms. This means that the hydrogen atoms are not strong enough to bend the electron pairs surrounding the oxygen nucleus away from their tetrahedronal conformation. Therefore, the hydrogens end up closer to two points of a tetrahedron (at 109 degrees) rather than in a linear fashion like the carbon dioxide molecule (at 180 degrees).

Answer 7

Because it didn"t break? (just kidding. You already received the correct answer.)

Answer 8

it just is

it makes snow hexagonal

Answer 9

so it can be a liquid