The Lewis concept of acids and bases, proposed by Gilbert N. Lewis in 1923, provides a broader understanding of acid-base behavior beyond the traditional Arrhenius and Brønsted-Lowry theories. According to the Lewis concept, an acid is defined as a substance that can accept a pair of electrons, while a base is a substance that can donate a pair of electrons. This concept helps explain the behavior of protonic acids, which are substances that can donate a proton (H+) in a chemical reaction.

Explanation:
- The Lewis concept of acids and bases is a more inclusive theory that goes beyond the limitations of the Arrhenius and Brønsted-Lowry theories. It focuses on the electron-pair transfer in chemical reactions.
- According to the Lewis concept, an acid is a substance that can accept a pair of electrons to form a coordinate covalent bond. This means that acids are electron pair acceptors.
- On the other hand, a base is a substance that can donate a pair of electrons to form a coordinate covalent bond. Bases are electron pair donors.
- Protonic acids are substances that can donate a proton (H+) in a chemical reaction. In the Lewis concept, this behavior can be explained by the fact that the proton can accept a pair of electrons from a base, forming a coordinate covalent bond.
- When a protonic acid donates a proton, it becomes a conjugate base, which is the species that remains after the acid has donated a proton.
- In the Lewis concept, amphoteric substances are substances that can act as both acids and bases, as they can both accept and donate a pair of electrons. This behavior is explained by their ability to form coordinate covalent bonds with other substances.
- Lewis acids and bases can also form complexes with each other, where the Lewis acid accepts a pair of electrons from the Lewis base, forming a coordinate covalent bond.
- Salt is not specifically explained by the Lewis concept of acids and bases, as it refers to the product of a neutralization reaction between an acid and a base, according to the Arrhenius or Brønsted-Lowry theories.

In summary, the Lewis concept of acids and bases provides a more comprehensive explanation of acid-base behavior, including the behavior of protonic acids and amphoteric substances. It focuses on the transfer of electron pairs in chemical reactions, allowing for a broader understanding of acid-base interactions.