Why Are Transition Metals Called Transition Metals?

Colored Transition Metal Solutions
Many transition metal solutions are brightly colored. From left to right, aqueous solutions of: cobalt(II) nitrate; potassium dichromate; potassium chromate; nickel(II) chloride; copper(II) sulfate; potassium permanganate. Ben Mills

Question: Why Are Transition Metals Called Transition Metals?

Answer: Most of the elements on the Periodic Table are transition metals. These are elements that have partially filled d sublevel orbitals. Have you ever wondered why they are called transition metals? What transition are they undergoing?

The term dates back to 1921, when English chemist Charles Bury referred to a transition series of elements on the periodic table with an inner layer of electrons that was in transition between stable groups, going from a stable group of 8 to one of 18, or from a stable group of 18 to one of 32. Today these elements are also known as d block elements. The transition elements all are metals, so they are also known as transition metals.

While the metals get their names because of what's going on in their valence electron shell, it's easiest for students to remember these elements act as a bridge between the highly metallic alkali metals and alkaline earths on the left side of the periodic table and the nonmetallic nonmetals, halogens, and noble gases on the right side of the periodic table. So, they transition between metallic and nometallic properties.
Transition Metal Properties | List of Transition Metals