What is the ionized and unionized form?

[MitsuShai]

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


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

 

[Mike H]

Ions are atoms/molecules where the total number of electrons does not equal the total number of protons. If you have more electrons than protons, one has an anion - a negatively charged ion. If you have more protons than electrons, one has a cation - a positively charged ion. And then you can also have zwitterions.

Remember, amino acids can be zwitterions. They have both a carboxylic acid functional group and an amine functional group. The protonation state for the two groups will vary as a function of pH. This, it seems, is the source of the confusion, based on what you've written.