How Does Hydrogen Donate a Proton with Only One?

[Witcher]

Homework Statement

I have a question that is more about why and less about how. If i am posting in the wrong section for my question i apologize ahead of time and ask that you direct me to the correct forum.

Relevant Equations

HCO3-(aq) + H2O(l) -> H2CO3(aq) + OH (aq)
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My question for Bronsted Lowry chemical equation is about the donating and accepting electrons. In the bottom chemical equation, the acid is a proton donor. How can hydrogen donate a proton when it has only 1? Or is the subscript the proton in chemical equations

 

[chemisttree]

...Or is the subscript the proton in chemical equations...

No, the proton is the proton in chemical equations.

In your example, water is the proton donor. Proton cannot be the proton donor, as you have surmised.