Chemistry is basic to essentially every field of science. A working knowledge of chemistry informs medicine, energy production and the vast majority of industrial processes. A comprehensive theory of chemistry allows predictions to be made about how any substance in the universe will behave in the presence of any other substance.
The study of chemistry only became truly scientific after discarding the baggage it inherited from the earlier practice of alchemy. A crucial step on this path was the development of a true unifying theory of the elements that explained their observed behavior and made testable predictions about the compounds they form. Applying this theory greatly eases the task of virtually every geologist, medical researcher and engineer in the world.
Geologists apply their understanding of chemistry to explain the formation of certain minerals, such as hematite, that would be mysterious otherwise. Biologists could be said to work in applied organic chemistry, as life is virtually nothing but very sophisticated carbon-based chemistry. The importance of chemistry to the pharmaceutical industry, as well as to the petroleum industry and the materials fabrication economy, could hardly be overstated. The study of chemistry is also important for anyone interested in pursuing a career in advanced nursing or nutrition.