An idea is much more than a chemical reaction in your brain! It is worth quoting an article from Wikipedia:
An idea is a form (such as a thought) formed by consciousness (including mind) through the process of ideation. Human capability to contemplate ideas is associated with the ability of reasoning, self-reflection, and of the ability to acquire and apply intellect, intuition, inspiration, etc.. Further, ideas give rise to actual concepts, or mind generalisations, which are the basis for any kind of knowledge whether science or philosophy or impulsiveness.
In a popular sense, an idea arises in a reflex, spontaneous manner, even without thinking or serious reflection, for example, when we talk about the idea of a person or a place.
There is an interesting discussion on Wikipedia concerning ideas and it is worthy of a read at: http://en.wikipedia.org/wiki/Idea
From my reading of the article and the discussion by the contributors it is clear that ideas and innovation go hand in hand. What do you think?