What is meant by the chelate effect? Give an example.

(N/A) When a ligand attaches to the metal ion in a manner that forms a ring,the metal-ligand association is found to be more stable. In other words,complexes containing chelate rings are more stable than complexes without rings. This is known as the chelate effect.
For example:
$Ni_{(aq)}^{2+} + 6NH_{3(aq)} \to [Ni(NH_3)_6]_{(aq)}^{2+}$
$(\log \beta = 7.99)$
$Ni_{(aq)}^{2+} + 3en_{(aq)} \to [Ni(en)_3]_{(aq)}^{2+}$
($\log \beta = 18.1$ (more stable))
The structure of $[Ni(en)_3]^{2+}$ shows the formation of chelate rings with ethylenediamine $(en)$ ligands.