Which one of the following has the highest ionic character?
BeF₃
SiO₂
NCl₃
K₂S
Answer is Right!
Answer is Wrong!
This question was previously asked in
UPSC CDS-1 – 2024
Electronegativity differences:
– BeF₃ (assuming Be-F bond in a compound): |4.0 – 1.5| = 2.5. Be compounds often show significant covalent character due to Be²⁺’s high charge density.
– SiO₂ (Si-O bond): |3.4 – 1.9| = 1.5. SiO₂ is a covalent network solid.
– NCl₃ (N-Cl bond): |3.2 – 3.0| = 0.2. This is a covalent molecule.
– K₂S (K-S bond): |2.5 – 0.8| = 1.7. K is a Group 1 metal, S is a non-metal. The bond is predominantly ionic.
While Be-F bond has a larger electronegativity difference, K₂S is formed between a highly electropositive alkali metal (K) and a chalcogen (S), resulting in a typical ionic compound with K⁺ and S²⁻ ions in an ionic lattice. K₂S exhibits more characteristics of an ionic compound compared to BeF₂ (often described as having significant covalent character or being polymeric/covalent in gaseous state) or the definitively covalent SiO₂ and NCl₃.