Ligands bond to metals by using their lone pair of electrons.
- The metal has empty orbitals.
- The ligand gives (donates) its electrons to the metal.
- This makes a coordinate bond (special covalent bond).
Some ligands use one atom to bond (like H₂O, NH₃).
Some use two or more atoms (like EDTA), so they hold the metal more strongly.
In short: Ligand = electron giver, Metal = electron taker → they stick together.