Ethylenediaminetetraacetic acid EDTA is a chelating agent used in chelation therapy for the treatment of lead poisoning. The role of EDTA in this therapy is to bind with lead ions Pb2+ present in the body, forming a stable, water-soluble complex that can be easily excreted through the kidneys, thereby reducing the toxic effects of lead on the body.The coordination chemistry behind EDTA's ability to remove lead ions from the body involves the formation of a coordination complex between the EDTA molecule and the lead ion. EDTA is a hexadentate ligand, meaning it can bind to a central metal ion in this case, lead through six donor atoms. The EDTA molecule has four carboxylate groups -COO- and two amine groups -NH2 that can act as electron-pair donors to form coordinate covalent bonds with the lead ion.When EDTA binds to the lead ion, it forms a highly stable octahedral complex, with the lead ion at the center and the six donor atoms from the EDTA molecule surrounding it. The stability of this complex is due to the high denticity of the EDTA ligand and the strong affinity of lead ions for oxygen and nitrogen donor atoms. This stability is quantified by the formation constant Kf , which is very high for the Pb-EDTA complex, indicating a strong preference for the formation of this complex over other potential complexes with other metal ions in the body.Once the Pb-EDTA complex is formed, it is water-soluble and can be easily filtered by the kidneys and excreted in the urine. This process helps to remove lead ions from the body, reducing their toxic effects and alleviating the symptoms of lead poisoning.