If nitrogen, carbon, and oxygen all form sp3 orbitals, what reason is there for NH3 and H20 being polar and ..

Question

while CH4 is not?

Answer 1

The reason why ammonia (NH3) and water (H20) are polar is because they have uneven distribution of electron density while methane (CH4) is evenly distributed of electron density. CH4 have the same forces being pulled all four ways while NH3 and H20 don't.Water is polar because of the 2 lone pairs. Theoretically, if there was H40, it would be a non-polar. Again, if there was NH4, it would be non-polar too.

Answer 2

Nitrogen has a pair of electrons already in the orbital and it forms molecules with one C3 axis of symmetry. This means the the NH3 molecule will have more electron density on the nitrogen atom.

Oxygen has two pairs of electons already in the orbital but it forms flat planar molecules. If you consider it's symmetry, it's a C2 symmetry but more important to note is that H2O has a 120 degree angle (looks like Mickey Mouse ears like this °O° ), so it too has more electron density on the oxygen atom.

Carbon has no pairs of electons so it forms four covalent bonds which have C3 symmetry through each bonding axis. The electron distribution is evenly distributed about it's center. Therefore there is no polarity.

Answer 3

C needs 4 covalent bonds to complete its orbital, so all the 2s and 2p electron pairs are shared between C and H. That makes the molecule symmetrical so there is no polar end.

In NH3 and H2O, there are one or two (respectively) electron pairs that belong to the central atom alone, while the other (three or two, respectively) pairs are shared with hydrogen atoms. The unshared electron pairs are exposed to other molecules, thus creating a negatively charged end to the molecule.

Answer 4

draw out the vsper sketch for this and you will be able to see the answer easily. polarity depends on the location of the electrons. if they are equally distanced from eachother than they are nonpolar(because then you have different charges at each end.) you need the 3-d drawing though, lewis won't work.