Saturday, May 16, 2009

Chemistry Library

This week's code is probably the biggest single release I've ever made. I considered splitting it up into two or three weeks, but that would be too much work. Before we get started, you'll need my proper case function.

In this function library, we have three major things going on: look up chemical element symbols by atomic number, look up chemical element names by atomic number, and figure out the electron configuration of an atom given the atomic number.

For the chemical element names and symbols, I made an array of all the named elements; currently the highest named element is atomic number 111. There are elements with higher atomic numbers that have been discovered, but not yet named. There is also the possibility that more elements may be discovered in the future. To handle both these situations, I wrote code to generate standardized names if the array lookup fails.

The function(s) for figuring out electron configuration are my favorite. I started with an array of all the subshells in the order they get filled. Then I wrote a function that knows how many electrons can fit in each type of subshell. Finally, I wrote the main function which fills the subshells, taking into account known exceptions to the rules. (e.g. palladium)

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