Chemistry is the science of the composition, structure, properties, and reactions of matter, especially of atomic and molecular systems. One who studied chemistry was known as a chemist.
In the Julian Bashir, Secret Agent holoprogram, Mona Luvsitt had degrees in physics and chemistry, as well as biology. (DS9: "Our Man Bashir")
In 2384, it was among the branches of science shown to Rok-Tahk when she was attempting to choose a specialty. (PRO: "Asylum")