Fill in the blanks by choosing the appropriate word/words from those given in the brackets: (double salts, complex compounds, uni, bi, six, four, three, coordination, linkage, imperfect, perfect, normal, penetrating, central ion, chelating, Werner, Pauling)
Polydentate ligands are also called.... ligands.

Explanation

To fill in the blank in the statement "Polydentate ligands are also called ____ ligands," we need to identify the appropriate term from the options provided.

### Step-by-Step Solution:

1. **Understanding Polydentate Ligands**:
- Polydentate ligands are molecules that can attach to a central metal ion at multiple points. This means they have multiple donor atoms that can coordinate with the metal ion.

2. **Identifying the Correct Term**:
...