Inorganic chemistry is the branch of chemistry involving the reactions, structures, and properties of all noncarbon-based compounds. This includes all the chemical elements in their pure and semipure states (except carbon). Some simple carbon compounds, including carbon monoxide, carbon dioxide, and hydrogen cyanide, are nevertheless considered to be in the realm of inorganic chemistry.

The lines of definition are becoming increasingly blurry between inorganic chemistry and such other major areas of the science as physical chemistry, biochemistry, and even organic chemistry, due to the fields' many common interests. However, inorganic chemistry is unique in that it is the only branch of chemistry that specifically excludes the element carbon.

The modern concept of inorganic chemistry is virtually unrelated to the original sense of the word, which was strictly taken to mean "not living." Until the beginning of the twentieth century, scientists believed that all living things (animals...