The mole is currently considered a base unit in the SI system, but it was not always the case. Until 2019, it was defined as a derived unit, which was dependent on the kilogram, which is one of the seven SI base units. However, the mole was redefined in 2019 as an independent base unit, with a fixed value based on the Avogadro constant, which is a fundamental constant of nature.
The mole is a crucial unit in chemistry, as it provides a means to measure the amount of a substance on a molecular scale. It is a unit of measurement for the number of particles (such as atoms, molecules, or ions) in a given sample. Thus, the mole is not a unit of measure in the way that meters, seconds, and kilograms are. Instead, it is a measure of the number of particles present in a sample, and it is used to calculate other properties such as molar mass, molarity, and stoichiometry.
While calculations performed with the number of moles of a substance could also be performed with the number of particles of a substance, the mole is still considered a base unit in the SI system because it is a fundamental unit that provides a bridge between the macroscopic and microscopic worlds. It is an essential unit for chemists and physicists, and its inclusion as a base unit in the SI system reflects its importance in these fields.
In summary, while the mole is not a unit of measure in the same way as meters, seconds, and kilograms, it is still considered a base unit in the SI system because of its importance in chemistry and physics. Its inclusion as a base unit reflects its fundamental role in these fields, and its recent redefinition as an independent base unit highlights its significance as a measure of the number of particles in a sample.