A Dalton (Da) is a unit of mass used in the field of chemistry and molecular biology to express the molecular weight or mass of atoms, molecules, and compounds. It is named after John Dalton, a British chemist and physicist who contributed to the development of modern atomic theory.
One Dalton (Da) is defined as one twelfth of the mass of an unbound carbon-12 atom, which is roughly equivalent to 1.66053906660 x 10^-27 kilograms. This definition was adopted as the standard for atomic mass units (u) and is now used internationally.
Daltons are useful in the following contexts:
Atomic and Molecular Mass: The molecular weight or mass of a molecule is often expressed in Daltons. For example, the molecular weight of water (H2O) is approximately 18.01528 Da, which means that one molecule of water has a mass of approximately 18.01528 Daltons.
Proteomics and Biochemistry: In biology, particularly in the study of proteins, the mass of biomolecules like proteins and nucleic acids is often measured in Daltons. This is important for understanding their structure and function.
Mass Spectrometry: Mass spectrometry is a powerful analytical technique used to determine the mass and composition of molecules. Mass spectrometry results are often reported in Daltons.
Chemical Reactions: In chemical reactions, the mass of reactants and products can be expressed in Daltons to understand the stoichiometry of the reaction.
n the United States, the term "stone" is not a commonly used unit of measurement for weight or mass in everyday contexts. Instead, the United States primarily uses pounds (lbs) to measure weight. One pound is equal to approximately 0.0714 stones.
However, the "stone" is a traditional unit of weight used more commonly in the United Kingdom and some other countries, but it is not part of the standard metric system.
1 stone (UK) = 14 pounds (lbs)
So, when you encounter the term "stone" in the context of weight or mass in the United States, it's typically used informally or in specialized contexts where individuals may be familiar with this unit of measurement due to cultural or international exposure.