The standard for the atomic mass scale is currently the Carbon atom, specifically Carbon-12, which is defined as 12 unified atomic mass units (amu). The discussion explores whether another atom could serve as this standard, with suggestions including Lithium-7, which could be defined as exactly 7.0000 amu. The precision of atomic mass definitions can vary, and the choice of standard atom should consider factors like availability, safety, cost, and ease of purification. Historically, the standard was changed from Oxygen-16 to Carbon-12 in 1961 to minimize disruption in existing measurements, as Oxygen-16 was believed to be the only isotope of oxygen prior to the discovery of isotopes. The conversation raises questions about the necessity of changing the standard and the implications of such a change.
