Here's why:

* Hydrogen (H) is usually +1: Hydrogen atoms typically have a +1 charge when forming compounds.

* Bicarbonate (HCO3-) is -1: The bicarbonate ion (HCO3-) carries a -1 charge.

If you were to combine one hydrogen ion (H+) with one bicarbonate ion (HCO3-), you would get H2CO3, which is carbonic acid.

There is no known compound with the formula HHCO3.