The compound with the maximum 'lone pair-lone pair' electron repulsions can be determined by examining the electron configurations and molecular geometry of each molecule. Below is an analysis of each molecule to determine which has the greatest number of lone pairs and thus maximum repulsions:
- ClF3: Chlorine has 7 valence electrons, and forms three bonds with fluorine atoms, leaving behind 2 lone pairs. It has a T-shaped molecular geometry.
- IF5: Iodine has 7 valence electrons and forms five bonds with fluorine atoms, leaving behind 1 lone pair. It has a square pyramidal molecular geometry.
- SF4: Sulfur has 6 valence electrons and forms four bonds with fluorine atoms, leaving behind 1 lone pair. It has a seesaw shape.
- XeF2: Xenon has 8 valence electrons and forms two bonds with fluorine atoms, leaving behind 3 lone pairs. It has a linear geometry.
From this analysis, XeF2 with 3 lone pairs exhibits the maximum 'lone pair-lone pair' repulsions as each lone pair occupies more space and repels the others strongly. Compared to the other molecules, no other has as many lone pairs, thus XeF2 will have the maximum repulsions due to its lone pairs.
Conclusion: The molecule XeF2 has the highest 'lone pair-lone pair' electron repulsions.