Inspired by [this question][1], I'm wondering why arsenous acid is frequently denoted $\ce{H3AsO3}$, as opposed to $\ce{As(OH)3}$, which would appear to more accurately reflect its connectivity?


  [1]: http://chemistry.stackexchange.com/questions/472/what-are-the-mechanisms-for-capture-of-ceasiii-and-ceasv-by-magnet