Why is ozone a greenhouse gas?

Question

I always thought that a greenhouse gas molecule must have a dipole moment, created by an unequal affinity for electrons between the atoms in the molecule. So, for example, water vapor and CO2 have a dipole moment because of the high electronegativity of oxygen compared to carbon or hydrogen. This creates a small negative charge around the oxygen atoms and a small positive charge on the carbon or hydrogen atoms, allowing the molecule to generate an oscillating electric field if it bends or stretches.

This, I understood, is why N2 and O2 are NOT greenhouse gases: each of the two atoms in these molecules will obviously have equal electronegativity since they are the same element, and so there will be no imbalance of charge, and hence no dipole moment.

So why, then, is ozone an effective greenhouse gas? If all three atoms in the molecule are still oxygen, shouldn't they all attract electrons equally well, and hence shouldn't we have an overall neutral molecule that is incapable of creating an oscillating electric charge? What is it about having three oxygen atoms instead of only two that allows ozone to be a greenhouse gas while regular O2 is not?

Answer 1

Rotational transitions are associated with a permanent dipole moment, while vibrational transitions are associated with \changes/ in the dipole moment. CO2 has no permanent electric or magnetic dipole moment because it's a linear molecule. Only during asymmetric stretch and bending vibrational modes does the linear symmetry break allowing for an oscillating dipole moment. CH4 has no dipole moment either, but again, symmetry breaks down during certain vibrational motions.



O3 has nonpolar bonds, but the overall molecule is polar because of unequal distribution of charge. In O3 the central oxygen atom has a formal charge of +1, while the single bonded oxygen has a formal charge of -1. It's this separation of charges that creates the dipole moment.



Heteronuclear diatomic molecules like HCl and CO are greenhouse gases because they are polar, and the magnitude of their dipole moment changes during their only vibrational mode: stretching. It's the change in dipole moment during a vibrational transition that makes a molecule infrared active, and thus, a greenhouse gas.



BTW, O2 has a permanent magnetic moment because of aligned spin of the unpaired electrons in the oxygen molecules. This allows a rotational spectra in the microwave region.

Answer 2

Is Ozone A Greenhouse Gas

Answer 3

This Site Might Help You.



RE:

Why is ozone a greenhouse gas?

I always thought that a greenhouse gas molecule must have a dipole moment, created by an unequal affinity for electrons between the atoms in the molecule. So, for example, water vapor and CO2 have a dipole moment because of the high electronegativity of oxygen compared to carbon or hydrogen. This...

Answer 4

Ozone traps or block UV rays which dont contain heat energy, it is the Infra Red which contains and transfer Heat energy so any gas which affect the IR in its function can be called GHG, Water vapour is the major contributer and is the reason we have seasons. Ozone does not affect IR much though it contributes 3-7 % of GHG effect according to Wikipedia but when it is generated in Trophosphare so yes it is a GHG.

Answer 5

A greenhouse gas is a gas with three or more molecules in it. If it has a dipole, it just has more modes of oscillation, broadening the absorptions bands and adding a few.



Oxygen and nitrogen also are tightly bound (besides not having a dipole), and consequently don't react to anything short of ionizing radiation (UV-C and more energetic, but they do play with some visible light... just not strongly).



Ozone is bonded O-O=O, is angular (so it has a dipole), and it swaps state: O=O-O.



Greenhouse gases can have the central atom vibrate (so infrared), can spin and flip (microwaves).



[EDIT: "But why three?"



Its "three or more". Because the central atoms can oscillate between the end / exterior atoms, this can store a lot of energy, and responds to infrared, as I said. It has nothing to do with equal bond lengths, double bonds, unequal bonds or any such thing when dealing with infrared. Infrared does not itself ionize (well, not for the usual atmospheric gases anyway), so it is assumed the bonds hold up to brief dances with packets of infrared energy.



Think of the Three Stooges (who?), with Moe in the middle, slapping Larry on one side, then Curly on the other. You can't do that with just two atoms, at infrared energies.]

Answer 6

Great question and answers and if you can follow how it works then it's the reason why this is the main cause for what we are seeing regarding global warming/climate change http://globalmicrowave.org/microwaves.php

http://www.animations.physics.unsw.edu.au/jw/EMspectrum.html

http://en.wikipedia.org/wiki/Radio_propagation