Here's why:
* Structure: Hydrogen carbonate consists of one hydrogen atom, one carbon atom, and three oxygen atoms.
* Electronegativity: Oxygen is more electronegative than both hydrogen and carbon. This means oxygen attracts electrons more strongly.
* Charge Distribution: The oxygen atoms in hydrogen carbonate pull the shared electrons closer to themselves, leading to a partial negative charge on each oxygen atom. The carbon atom also develops a slight positive charge, and the hydrogen atom has a partial positive charge.
* Overall Charge: Due to the uneven distribution of electrons, the molecule carries a net negative charge. This is why it's often written as HCO₃⁻.
Therefore, hydrogen carbonate is an anion, not a cation, and it does not contain a positive charge.
