Which term describes a compound that can both donate and accept protons?

• A. Amphiprotic species
• B. Bronsted-Lowry
• C. Amphoteric species
• D. Polyprotic acid

Answer: (A)

The ability to donate and accept protons is described by amphiprotic species. This means the substance can act as an acid in one reaction (donating a proton) and as a base in another (accepting a proton). A classic example is the bicarbonate ion, HCO3−: it can donate a proton to become CO3^2− or accept a proton to form H2CO3. This dual proton-transfer capability is what defines amphiprotic behavior. In contrast, the term Bronsted-Lowry refers to the acid-base theory itself rather than a property of a particular compound; amphoteric describes substances that can react with acids and bases more broadly, and polyprotic acid refers to an acid that can donate multiple protons but doesn’t address accepting protons. Hence, amphiprotic species is the best fit.