[Off-topic] xaccers:
Water molecules are heated by MW radiation because the frequency used in a MW oven (a different frequency to what is used in phones) allows the MW radiation to be absorbed by water, fats and sugar, causing the molecules within to vibrate.

This is because they try to line up with the photons as water/fats/sugars contain polar molecules. As the waves are alternating, the molecules rotate back and forth producing heat (which is a measurement of kinetic energy).

Change the frequency and nothing happens.

Even if it were at MW oven frequencies, with the ridiculously low energy levels involved the body's blood circulation would prevent any heat build up. Your brain doesn't get hot on a sunny day for instance, and that is receiving much higher levels of EM and thermal radiation from the Sun.

Your teachers need to cover scientific methodology, especially cause and effect, more as you've gone from roofrider's mention of a study (of just 47 people) showing mobile phone use resulted in a tiny bit more brain activity to mobile phone radiation causes increased brain activity.

Even those who actually did the study do not know what is causing the additional brain use. While they had mobile phones on both sides of the test subjects, they only ever activated the right hand one. Perhaps they too need a refresher lesson on scientific methodology...

Ionic chemistry is far simpler than organic chemistry. It's just balancing equations, and you don't have electrophiles, nucleophiles, or covalent bonds *shudders with the memories*

Photon absorption and emission are due to a quantum of light, which is a photon. Quantum meaning "a minimum amount involved" and nothing special. People hear Quantum mechanics and go all gooey about it.

Remember this is totally not what happens with MW heating.

So, pin your lug holes back (your ears) and get a pen and paper :)

The energy of a photon depends on it's wavelength/frequency.

Think of a row of Hertz rental cars all doing 60 kmph on the motorway passing your window. They all have to be the same distance apart (they're those funky self driving cars).

Now if they're a 17m apart (wavelength) they'll have a frequency of 1 car per second (1 Hertz).

If they increased their frequency to 2 Hertz, they'll have to half the distance between them (half their wavelength).

Got the link between wavelength and frequency? Good.

Now to work out the energy of a photon you need the following equation:

h is Planck's constant which is 6.626 × 10^-34 joules

c is the speed of light in a vacuum which is c = 2.998 × 10^8 m/s

Lambda is the wavelength.

So depending on the wavelength, photons have different energies. If they hit an electron with the right energy it will bump that electron into a higher "orbit" around the nucleus, and the photon is absorbed.

The electron loses a bit of energy as kinetic and can no longer remain in the excited state so returns to it's rest state by emitting the remaining extra energy as a photon with a longer wavelength (lower energy) hence why UV light can cause florescence.

If a photon has an energy that doesn't match the energy differences between the electron orbits, it will pass by and have no effect. This is why MW radiation doesn't affect electrons, because they're of the wrong wavelength.

So if no atoms have electron orbits matching MW wavelengths, how are they produced?

Well, if you run a current through a load of electrons with the right energy level, you excite them, then when they return to rest they release that energy as photons.