Why do transition metals often make colored compounds?
Quick Answer
Transition metals often form colored compounds because their d electrons can absorb specific wavelengths of light when the atoms are in compounds. The remaining reflected light is what we see as color.
The Full Story
Many transition metals, such as iron, copper, chromium, and cobalt, have partially filled d electron subshells. In compounds, those d electrons can be split into different energy levels by surrounding ions or molecules, and visible light can excite electrons between those levels. Different energy gaps absorb different colors, so the transmitted or reflected light looks colored. This is why copper compounds, for example, can appear blue or green, while many iron compounds are yellow, brown, or red.
Key Facts
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