Transition metals are elements found in the middle block (d-block) of the periodic table, between groups 3 and 12. They are called “transition” metals because they form a bridge between the highly reactive metals on the left side of the table and the nonmetals on the right.
Key characteristics of transition metals:
- They can form variable oxidation states (more than one type of positive ion).
- They often form colored compounds.
- They act as good catalysts in many chemical reactions.
- They are usually hard, dense, and have high melting points.
- They are good conductors of heat and electricity.
- They can form complex ions with ligands.
Examples include iron, copper, nickel, zinc, silver, and gold. Transition metals are very important in industry, construction, and biological systems (for example, iron in hemoglobin).