I thought there was going to be some crazy matching up of all the "shells" now into the 5-by-5 grid and having all the "P"s stand for something. They certainly did, of course, but I was never getting there. In retrospect, I wish I did since I also tutor chemistry, but if you don't see it, you don't see it.
I probably would've went with "7-letter word" on the prompt, since I was a bit surprised that SILICON actually worked! (I'm also assuming 1s2 2s2 2p6 3s2 3p2 is in play with the "E"s representing electrons in the corresponding shells!)