SI System of Measurement

Background The English system of measurement originated in 1215 with the signing of the Magna Carta. It attempted to bring uniform measurements to world trade. In 1790, the French government appointed a committee of scientists to develop a universal measuring system.

It took ~10 years, and they unveiled the metric system. length. meter It took ~10 years, and they unveiled the metric system. length meter m mass gram g volume liter L time second s

The International System of Units (Systeme International d’unites) was developed in 1960 from the older system. It is the world’s most widely used system of units, both in commerce and science. A notable exception is the United States, which still uses many old units in addition to SI.

SI Base Units in Chemistry Quantity Name Symbol length meter m mass kilogram kg time second s amount of substance mole mol temperature Kelvin K

Prefixes in the SI System Prefix. Symbo Meaning. Power of 10 mega-. M Prefixes in the SI System Prefix Symbo Meaning Power of 10 mega- M 1,000,000 106 kilo- k 1,000 103 hecto- h 100 102 deka- da 10 101 1 100 deci- d .1 10-1 centi- c .01 10-2 milli- m .001 10-3 micro- µ .000001 10-6 nano- n .000000001 10-9

Conversion of SI Units M k h da - d c m µ n 106 103 102 101 100 10-1 10-2 10-3 µ n 10-6 10-9

For example: 3 km = ____ cm From 103 to 10-2 is 5 powers of 10 to the right on the diagram. We will move the decimal place in the starting number 5 places to the right.

3 km = ____ cm Solution: 3. becomes 300,000 3 km = ____ cm Solution: 3. becomes 300,000. Therefore, 3 km = 300,000 cm

Likewise: 2.5 mm = ____ dam Solution: From 10-3 to 101 is 4 powers of ten to the left on the diagram. 2.5 becomes 0.00025 2.5 mm = 0.00025 dam