What is the color of potassium chromate, a compound containing a transition metal?

Potassium chromate is known for its distinct yellow coloration. This yellow hue arises from the presence of the chromate ion (CrO4^2-), which contains chromium in a +6 oxidation state. The chromate ion exhibits strong light absorption properties that contribute to its yellow appearance.

Understanding the color of transition metal compounds like potassium chromate involves considering the electronic transitions within the d-orbitals of the metal ion. In this case, chromium's electronic configuration allows the chromate ion to absorb certain wavelengths of light in the visible spectrum, ultimately reflecting the yellow light that we perceive.

In contrast, the other colors listed—blue, red, and green—are not characteristic of potassium chromate. Transition metal compounds can exhibit a variety of colors due to different oxidation states and ligands; however, potassium chromate's signature yellow color is a well-known and documented aspect of its chemical identity.