SI in chemistry does not stand for a specific chemical substance. Instead, SI stands for the International System of Units (Système International d'unités). It's the modern form of the metric system and is the most widely used system of measurement in science, including chemistry.
In contrast, "Si" is the chemical symbol for the element Silicon, as referenced in the provided document. It's important to differentiate between "SI" (two letters) and "Si" (one uppercase and one lowercase letter) in chemical contexts.
Therefore, when referring to measurements and units in chemistry, SI refers to the International System of Units.
