Differentiate between `VB` theory and Lewis concept.

Explanation

### Step-by-Step Solution

1. **Definition of Covalent Bond:**
- **Lewis Concept:** According to Lewis concept, a covalent bond is formed by the mutual sharing of electrons between two atoms. This sharing allows each atom to achieve a stable electron configuration, typically resembling that of noble gases.
- **Valence Bond (VB) Theory:** In contrast, the Valence Bond theory states that a covalent bond is formed by the overlapping of half-filled atomic orbitals from two atoms. This overlap allows for the pairing of electrons with opposite spins, leading to bond formation.

2. **Mechanism of Bond Formation:**
- **Lewis Concept:** The Lewis concept emphasizes the idea of electron sharing without delving into the specifics of atomic orbitals or electron spins. For example, in a molecule like CH₄ (methane), the bond forms as carbon shares its electrons with hydrogen atoms to complete their octets.
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