CHM 151 SP18 020 SI and Metric Prefixes

The SI system is the standard for the metric
system. All metric units are based on these defined
units, which is the kilogram for mass, meter for length, Kelvin for temperature and meter
cubed for volume, which is actually derived from the length standard. Despite what your text book says, there are
only a handful of SI units. Metric units are based on the SI standards. Metric base units are those that have no prefix. The base unit for mass in metric is grams
or g. For volume the base unit we will use is liter,
or l. For length, meter or m and for time, second
or s. You must know the difference between a base
metric unit and a prefixed metric unit. Base metric units do not have a prefix while
prefixed metric units do have a prefix. Prefixes give the metric system a wide range
of units, from the very large to the very small. Pause the video if you need to so you can
turn to to Table 1.6 in your text. You can see from Table 1.6 of your text that
metric prefixes have a name, a symbol and a power of ten definition. The difference between capital and lower case
letters is important! Capital M stands for mega, which is ten to
the sixth power, or a million, while lower case m stands for milli which is ten to the
negative third or a thousandth. Micro, on the other hand, is represented by
the Greek lower case letter m, or mu, and sort of looks like an italic u. Micro stands for ten to the negative six or
a millionth. Each metric prefix represents a unique power
of ten.

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