When an acid donates a proton, the species left behind is called its:

1. A Bronsted-Lowry acid is a proton donor. 2. When an acid donates a proton, the species that remains is called the conjugate base of the acid. 3. It gets that name because it reacts as a proton acceptor in the reverse reaction. 4. The conjugate acid is what a base becomes after accepting a proton. _Source: OpenStax Chemistry 2e (CC BY 4.0), Ch 14 'Acid-Base Equilibria', sections 14.1-14.7_