Relative mass is typically expressed in which units?

Relative mass, particularly when discussing the mass of atoms and molecules in the context of chemistry, is typically expressed in atomic mass units (amu). Atomic mass units provide a scale that simplifies the comparison of the masses of different atoms and molecules, allowing chemists to understand the relative sizes of these particles without dealing with the very small numbers involved in grams or milligrams.

For example, the atomic mass of carbon is approximately 12 amu, which means it is 12 times heavier than one twelfth of the mass of a carbon-12 atom. This unit is specifically designed for use in chemistry to facilitate calculations involving atomic and molecular masses, making it the standard choice for expressing relative mass.

In contrast, grams, kilograms, and milligrams are standard units of mass used for weighing larger quantities of substances and do not effectively represent the small relative masses encountered at the atomic level. Therefore, atomic mass units are the correct and most applicable choice for relative mass in chemistry.