Chelate ligands: the en ring and EDTAकीलेट लिगन्ड: en वलय और EDTAChelate ligands: the en ring and EDTA

NCERT §5.2(c) · Class 12 Chemistry · Chapter 5 · interactive diagram

Parts and what they mean

• Chelate ring (5-membered) (कीलेट वलय (5-सदस्यीय)) — M–N–C–C–N–(back to M): the didentate ligand grips the metal like a crab’s claw (Greek chele = claw).
• Metal ion (धातु आयन) — Bonded to both donor atoms of the same ligand.
• Donor N atoms (दाता N परमाणु) — Both N of en use their lone pairs simultaneously on ONE metal ion → chelate ligand.
• CH₂ groups (CH₂ समूह) — Complete the ring; they are not bonded to the metal.
• EDTA⁴⁻ backbone (EDTA⁴⁻ का ढाँचा) — One EDTA⁴⁻ wraps the ion and uses six donor atoms: hexadentate. Denticity = number of ligating groups = 6.
• Ca²⁺ (Ca²⁺) — Ca²⁺ and Mg²⁺ form stable EDTA complexes — the basis of hardness titration with Na₂EDTA.
• N donor of EDTA (EDTA का N दाता) — Two amine N atoms.
• O donor of EDTA (carboxylate) (EDTA का O दाता (कार्बोक्सिलेट)) — Four carboxylate O⁻ atoms.
• Chelate effect (कीलेट प्रभाव) — NCERT: chelate complexes tend to be more stable than similar complexes containing unidentate ligands.

Original diagram drawn by Simple Learning Hub, based on NCERT §5.2(c). Report a mistake