The term "bicarbonate" for HCO3 originates from an outdated naming system based on the historical observation of the compound's composition.
Historical Context of "Bi" in Bicarbonate
The prefix "bi" in bicarbonate is a remnant of an older chemical nomenclature system. This system predates our modern understanding of chemical bonding and structure. The "bi" prefix was used to denote the presence of twice as much carbonate (CO3) per sodium atom in sodium bicarbonate (NaHCO3) compared to sodium carbonate (Na2CO3).
Comparing Sodium Carbonate and Sodium Bicarbonate
Consider the chemical formulas:
- Sodium Carbonate (Na2CO3): Two sodium atoms for every carbonate.
- Sodium Bicarbonate (NaHCO3): One sodium atom for every carbonate.
In sodium bicarbonate, there appears to be "half" the sodium, or conversely, "twice" the carbonate, per sodium compared to sodium carbonate. Hence, the "bi" prefix was historically applied.
Modern Chemical Nomenclature
It is important to note that the "bi" prefix is largely outdated in modern chemical nomenclature. The systematic name for NaHCO3 is sodium hydrogencarbonate, which accurately reflects its chemical composition: it's a sodium salt of the hydrogencarbonate ion (HCO3-). The term "bicarbonate" persists, however, due to its widespread historical use and familiarity.
