
It is really difficult to get a good picture of your back. 
It's the periodic table of the elements, and the simplicity of its structure is one of my favorite examples of scientific beauty. Everything in our macroscopic world is made up of stuff in these boxes, and when you line them up by the number of protons like this, their columns (and general location) tell you quite a lot about their physical properties.
Other tattoos:
Just in case you were curious, here is a quick inventory of my other tattoos. All of them represent the inherent beauty that comes from our ability to look at the universe, and build an understanding of it with only a few simple symbols. To me, this is the prettiest art there is.
Right Calf: The SchrÃ¶dinger equation, and an electron trapped in a quantum well

This is the key to understanding how things behave at the subatomic level. 
Right Foot: The uncertainty principal

This captures the inherent randomness of our universe and our inability to observe it perfectly. The irony is that this one is starting to rub off, making it difficult to observe. 
Left Calf and Foot: Pi, out to 51 digits

This ratio is fundamentally tied to the curious fact that our universe has more than one spatial dimension. 
Left Bicep: Maxwell's equations

These four equations govern all of electricity and magnetism. Unfortunately for me, some assholes went and created a magnetic monopole in a laboratory, which violates the third equation, so now I have to go get an asterisk or something tattooed on there. 
Left Tricep: Electric field lines from static charges

A companion piece to maxwell's equations. All the field lines start on the positive charge and end on the negative charge. 
Left Shoulder: Magnetic field lines from a bar magnet

Another companion piece to maxwell's equations. Every line is a fully closed loop with no beginning and no end. 
Right Ribcage: List of martial arts I have studied

Taekwondo, kenpo, judo, wushu, muay thai, eskrima, and hapkido. I have studied a lot more than just these, but these were the ones I felt most shaped my journey as a martial artist. This is my only nonscience tattoo, but this is still art to me because it reminds me that I live in a place where all these cultures come together, and I can learn a little bit from each of them. 