EDTA is a hexadentate ligand.

Solution

Chemistry ma’am · 4 steps

Count the donor atoms in EDTA⁴⁻: two nitrogens and four carboxylate oxygens make six.

1. What denticity means. Denticity is the number of donor atoms in one ligand that bind to the same metal ion. A ligand that binds through six atoms is hexadentate.
2. Find the donors. EDTA is ethylenediaminetetraacetate, EDTA⁴⁻. Each of its two nitrogen atoms has a lone pair, and each of its four -COO⁻ groups gives one oxygen to the metal.
3. Add them up. 2 N + 4 O = 6 donor atoms. All six can wrap around a single metal ion, forming an octahedral chelate, as in [Ca(EDTA)]²⁻.
4. So. EDTA binds through six donor atoms, so it is a hexadentate chelating ligand. The statement is true.

The idea to keep. To find denticity, count the atoms that actually donate a lone pair to the metal, not the total atoms in the ligand. For EDTA, remember 2 N plus 4 O gives 6.

Answer from the NTA final answer key. Solution by PrepWiser.