What is the Lewis theory of acids and bases?

The Lewis theory is the most general way to define acids and bases. Here’s a explanation:

---

1. Acid (Lewis)

• A Lewis acid is a substance that accepts a pair of electrons.
• Example:
  • BF₃ + NH₃ → F₃B–NH₃
    • BF₃ accepts an electron pair from NH₃ → acts as a Lewis acid

---

2. Base (Lewis)

• A Lewis base is a substance that donates a pair of electrons.
• Example:
  • NH₃ + H⁺ → NH₄⁺
    • NH₃ donates an electron pair to H⁺ → acts as a Lewis base

---

Key Points

• Does not require H⁺ or OH⁻ ions.
• Focuses on electron pair transfer, not just protons.
• Includes more reactions than Arrhenius or Brønsted-Lowry definitions.

---

In short:

Lewis acid → takes electron pair
Lewis base → gives electron pair