Avogadro constant Avogadro constant In chemistry and physics, the Avogadro constant, named after scientist Amedeo Avogadro, is the number of constituent particles, usually atoms or molecules, that are contained in the amount of substance given by one mole. Thus, it is the proportionality factor that relates the molar mass of a substance to the mass of a sample. The Avogadro constant, often designated with the symbol "N" or "L", has the value in the International System of Units (SI). (The parentheses there represent the degree of uncertainty.) Previous definitions of chemical quantity involved the Avogadro number, a historical term closely related to
Hand (unit) Hand (unit) The hand is a non-SI unit of measurement of length standardized to . It is used to measure the height of horses in some English-speaking countries, including Australia, Canada, the Republic of Ireland, the United Kingdom and the United States. It was originally based on the breadth of a human hand. The adoption of the international inch in 1959 allowed for a standardized imperial form and a metric conversion. It may be abbreviated to "h" or "hh". Although measurements between whole hands are usually expressed in what appears to be decimal format, the subdivision of the hand is