Silicon monoxide is the chemical compound with the formula SiO where silicon is present in the oxidation state +2. In the vapour phase, it is a diatomic molecule. It has been detected in stellar objects and has been described as the most common oxide of silicon in the universe.

Clemens Alexander Winkler was a German chemist who discovered the element germanium in 1886, solidifying Dmitri Mendeleev's theory of periodicity.