Ionic bond is formed when 2 ions one with positive charge(s) and another with negative charge(s) chemically combines together, such as under heat.
Baking soda is also known as sodium bicarbonate (NaHCO3), which consists of sodium ions and bicarbonate ions.
Sodium ion brings 1 positive charge (Na+) meanwhile bicarbonate ion brings 1 negative charge (HCO3-). Therefore, when these 2 kind of ions combine together, one electron is transferred to a bicarbonate ion from a sodium ion, so that both of these ions can maintain a stable electron number.
Meanwhile, metallic bond is where atoms of only metals bond together, they all can make positive ions (but not used in metallic bonds), and covalent bond is where atoms of only non metals, they can all make a negative ion (also not used in covalent bonds).
Therefore, whenever a compound which consists of negative and positive ions bonded together, the bonding is ionic bond.