In which one of the following compounds, all the bonds are not equal?

CONCEPT:

Bond Equality in Molecules

• In a molecule, the equality of bonds depends on the symmetry and electronic environment around the atoms.
• If the molecule has a symmetrical structure and all the atoms around the central atom are identical, the bonds are usually equal.
• If the molecule has an asymmetrical structure or the surrounding atoms are different, the bonds may not be equal.

EXPLANATION:

• BF₃: Boron trifluoride has a symmetrical trigonal planar structure. All the bonds in BF₃ are equal because the fluorine atoms are identical and the electronic environment is the same.
  
• AlF₃: Aluminum trifluoride also has a symmetrical trigonal planar structure. All the bonds in AlF₃ are equal for the same reasons as BF₃.
  
• NF₃: Nitrogen trifluoride has a pyramidal structure due to the lone pair on nitrogen. However, all the bonds between nitrogen and fluorine are equal because the fluorine atoms are identical.
    
• ClF₃: Chlorine trifluoride has a T-shaped structure due to the presence of lone pairs on chlorine. In this molecule, the bonds are not equal because the fluorine atoms occupy different positions relative to the lone pairs, creating an asymmetrical electronic environment.
  
• Therefore, in the given compounds, ClF₃ is the one where not all bonds are equal.

Correct Answer: Option 4 (ClF₃)