# What is the ionized and unionized form?

So I'm doing a henderson hasselbach type problem.

I learned in biochemistry that the uncharged form is the conjugate base [A-] and the charged form is the acid [HA]. However, I looked up on google about the henderson hasselbach equation and found that the unionized form is [HA], while the ionized form is [A-]. I got it from this: http://www2.umt.edu/medchem/teaching/Lecture1-Pharmaceutics.pdf [Broken]

Does uncharged and unionized mean the same thing? I thought it did, but now I'm a bit confused.

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