ionization tendencies

I started to post this as a response to the thread about the periodic table but since I've gotten some criticism lately for assuming I know more than I do with replying to threads, I though I should post it as a separate thread to check my knowledge. Please read and respond with any corrections/critique.

Atoms are basically charge-balancing systems. So a stable (charge balanced) atom may not be electrostatically prone to give away electrons, but if bombarded with energy, it can lose some electron(s) due to the fact that the energy it was bombarded with is stronger than the force holding the electrons. An element's relationship to noble gasses is a guide to its behavioral tendencies in that atoms are most stable in a molecular configuration where the outermost "shell" is full. So metals, whose outer shell is nearly empty, are more likely to give up electrons as their nearly-empty shells are almost like "extra baggage" "hanging off" the more stable full shell of the previous level. Non-metals, on the other hand, can also give up electrons but they are more resistant to doing so because their outer electrons have formed relatively stable partial-shell configurations.

That last part is where I'm getting confused. I'm beginning to think that certain partial-shell configurations are more stable because, e.g. they have only paired-electrons, whereas an atom with, say, 7 electrons has an unpaired electron. Like I said, though, I'm getting confused with this so I hope I'm not completely perverting the way it is. Thanks in advance for any insight.