What are interstitial compounds? Why are such compounds well known for the transition metals?

Explanation

### Step-by-Step Text Solution

**Step 1: Define Interstitial Compounds**
Interstitial compounds are defined as compounds formed when small atoms, such as hydrogen, nitrogen, or carbon, occupy the interstitial spaces (voids) within the crystal lattice of a metal. These small atoms fit into the spaces between the larger metal atoms, creating a new compound.

**Step 2: Explain the Structure of Transition Metals**
Transition metals are known for their unique properties, which include the presence of large crystalline structures. These metals have a specific arrangement of atoms that creates significant voids or gaps within their lattice structure.

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