Transition metal: definition in chemistry
Transition metal: A metal in the d-block of the periodic table, groups 3 to 12. Strictly, it is an element whose atoms or common ions have a partly filled d subshell.
Transition metals are usually hard, dense and strong with high melting points, and most can form ions with several different charges. Many of their compounds are brightly colored, and many of the metals and their compounds are excellent catalysts. Zinc, cadmium and mercury are in the d-block but are often left out of the strict definition, because their d subshells stay full in their common compounds.
Examples
- Iron — forms both Fe²⁺ and Fe³⁺ ions
- Copper — its hydrated sulfate forms bright blue crystals
- Nickel — a catalyst for turning vegetable oils into margarine
- Titanium — light, strong and used in aircraft and hip replacements
On the periodic table
The transition metals fill the wide central block of the table, from group 3 to group 12, between the s-block on the left and the p-block on the right.