Chemistry is an experimental science. But if our experiments are to be reproducible,
we must be able to describe fully the substances we’re working with
their amounts, volumes, temperatures, and so forth. Thus, one of the most
important requirements in chemistry is that we have a way to measure things.
Under an international agreement concluded in 1960, scientists throughout the
world now use the International System of Units for measurement, abbreviated
SI for the French Système Internationale d’Unités. Based on the metric system, which
is used in all industrialized countries of the world except the United States, the SI
system has seven fundamental units . These seven fundamental units,
along with others derived from them, suffice for all scientific measurements.
Physical Quantity Name of Unit Abbreviation
Mass kilogram kg
Length meter m
Temperature kelvin K
Amount of substance mole mol
Time second s
Electric current ampere A
Luminous intensity candela cd
