Which of the following is NOT a characteristic of transition metals?

Transition metals are a distinct group of elements characterized by their unique properties. One of the most notable characteristics is the ability to form colored compounds. This property arises from the presence of partially filled d-orbitals, which allow for the absorption of visible light and subsequently, the emission of color. Additionally, transition metals are well-known for having variable oxidation states due to the presence of multiple electrons in their d-orbitals that can be lost or gained during chemical reactions.

Another key feature of transition metals is their capability to act as catalysts. Many transition metals facilitate a wide range of chemical reactions, often lowering the activation energy required and increasing the reaction rate without being consumed in the process.

In contrast, nonmetals typically lack these characteristics. They do not possess the metallic luster or conductivity associated with transition metals, and they generally do not exhibit variable oxidation states or form colored compounds. Thus, identifying that transition metals are primarily nonmetals is not correct, making this the answer that does not align with the characteristics of transition metals.