The chemical element that is most commonly associated with the color blue is Copper (Cu). When copper compounds are heated in a flame, they produce a blue-green color. This is often seen in fireworks and flame tests in chemistry labs.
Another example is Cobalt (Co), which is known for its deep blue color. Cobalt compounds are used in making blue pigments for paints and ceramics.
Additionally, Oxygen (O) in its liquid and solid states appears as a pale blue color. However, this is less commonly encountered in everyday situations.