The unit of atomic mass, the dalton (Da), is named after the British chemist and physicist John Dalton, who is known for his work on atomic theory. Dalton proposed that matter is composed of indivisible particles called atoms, each with a unique mass.
The choice to name the unit of atomic mass after John Dalton was primarily a tribute to his significant contributions to the development of atomic theory. The dalton serves as a convenient and widely used unit to express atomic and molecular masses.
The reason why the unit of atomic mass is not expressed in terms of grams or kilograms is because atoms and molecules are extremely small and their masses are typically on the order of atomic mass units (amu), which is a more suitable scale for such entities. The dalton (Da) is defined as 1/12th the mass of a carbon-12 atom, which is approximately equal to the mass of a single proton or neutron. It provides a more precise and specific measure for atomic and molecular masses.
By using the dalton as the unit of atomic mass, it allows for easier comparisons and calculations involving the masses of atoms, molecules, and subatomic particles, without the need for large numerical values or conversion factors associated with grams or kilograms.