Define the bond length.

Explanation

**Step-by-Step Text Solution:**

1. **Understanding Atoms in a Molecule**: Consider two atoms that are bonded together in a molecule. Let's label them as Atom 1 and Atom 2.

2. **Definition of Bond Length**: Bond length is defined as the equilibrium distance between the nuclei of two bonded atoms in a molecule. This means it is the distance at which the attractive forces between the atoms balance out the repulsive forces, resulting in a stable bond.

3. **Identifying Atomic Radii**: Each atom has a certain radius. Let's denote the radius of Atom 1 as \( r_1 \) and the radius of Atom 2 as \( r_2 \).

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