Measurement - Fundamentals of Chemistry - page 42

Figure 2.4 One-Kilogram
Samples
Note that the same masses of
strawberries, water, cubes of sugar,
iron, nails, and copper pennies have
different volumes.

primary unit is also the standard. With mass, however, the standard is different
from the unit. The gram is the primary unit of mass in the metric system. The
gram, abbreviated g, is such a small mass that the kilogram has been chosen as
the legal standard of mass in the United States and as the worldwide standard
in SI. Mass is measured by comparison with standard masses. The kilogram (kg)
is a mass equivalent to about 2.2 pounds (lb) (Figure 2.4).
The cubic meter is the primary unit of volume in SI. A smaller unit,
the liter, is the primary unit of volume in the metric system. The abbreviation
for liter is L. We need to know both the cubic meter and the liter. Table 2.3
summarizes the primary metric units of distance, mass, and volume.
The prefix centi- means one-hundredth of any primary unit. For example,
a centimeter (cm) is 0.01 m, and a centigram (cg) is 0.01 g.
The prefix milli- means one-thousandth. No matter which primary unit it is
used with, it always means 0.001 times that unit. A millimeter (mm) is 0.001 m,
a milliliter (mL) is 0.001 L, and so on.
The prefix kilo- means 1000 times the primary unit, no matter which
primary unit it is used with. For example, a kilogram (kg) is 1000 g, and a
kilometer (km) is 1000 m.

(m 3 )

Table 2.3

Primary Metric Units

Unit Symbol Equivalencies

Distance Meter m

Mass Gram g

Volume Liter L

m 3 1000 L 1 m 3 Volume Cubic meter

cm 3 1000 cm 3

Volume Cubic centimeter 1 L