Question

When a chemical loses a hydrogen ion, is it behaving as a chemical or a base? What is meant by "behaves as"?

Answer 1

It behaves as, which likely means that it fits into the definition for, a Bronsted-Lowry acid.

Explanation:

The Bronsted-Lowry acid-base theory defines acids as species that lose hydrogen ions (`H^+`, a.k.a. protons) in a chemical reaction (and bases as species that accept hydrogen ions.)

"A Brønsted-Lowry acid is a proton (hydrogen ion) donor." [1]

The chemical in question here loses protons and fits into the definition for Bronsted-Lowry acids.

Sources:
[1] Libretexts. “Brønsted Concept of Acids and Bases.” Chemistry LibreTexts, Libretexts, 21 July 2016, chem.libretexts.org/Core/Physical_and_Theoretical_Chemistry/Acids_and_Bases/Acid/Bronsted_Concept_of_Acids_and_Bases