When lithium (Li) and chlorine (Cl) atoms interact to form an ionic bond, their valence electrons undergo a rearrangement to achieve a stable electron configuration. Here's how it happens:

1. Initial Electron Configurations:

- Lithium (Li): 1s²2s¹ (3 valence electrons)

- Chlorine (Cl): 1s²2s²2p⁶3s²3p⁵ (7 valence electrons)

2. Electron Transfer:

- Lithium transfers its one valence electron to chlorine.

- Chlorine accepts this electron, becoming negatively charged.

- As a result, lithium loses an electron and becomes positively charged, while chlorine gains an electron and becomes negatively charged.

3. Formation of Ions:

- Lithium atom loses its only valence electron, resulting in a positively charged lithium ion (Li⁺) with a 1s² electron configuration.

- Chlorine atom gains an extra electron, resulting in a negatively charged chloride ion (Cl⁻) with a 1s²2s²2p⁶3s²3p⁶ electron configuration.

4. Ionic Bond Formation:

- The electrostatic attraction between the positively charged lithium ion (Li⁺) and the negatively charged chloride ion (Cl⁻) holds them together, forming an ionic bond.

In summary, the formation of an ionic bond between lithium and chlorine involves the transfer of one valence electron from lithium to chlorine, resulting in the formation of positively charged lithium ions (Li⁺) and negatively charged chloride ions (Cl⁻). These ions are then held together by the strong electrostatic forces of attraction between opposite charges, forming the ionic compound lithium chloride (LiCl).