# CHemistry Thingy - ACTIVITY 01-1 Units of Measurement WHY?...

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1WHY?Units identify the scale that is used in making a measurement and are essential for the measurementto be meaningful. For example, if someone tells you that a person is 60 tall, you do not knowwhether they are referring to a child or possibly an adult until you know the units. The units couldbe inches or centimeters, but probably are not feet or meters. In your study of chemistry and itsapplications, you need to be familiar with the basic units that are used for mass, length, time,temperature, electrical current, and amount of substance. Prefixes to the units make it quicker andeasier to write very large or very small numbers, e.g., 5,600,000 g = 5.6 Mg or 0.000001 s = 1μs.Other units are derived from these basic units. For example, units of volume are derived from unitsof length, and units of energy are derived from units of mass, length, and time. You also need to beable to convert from one set of units to another because different countries, disciplines, and evensub-disciplines of chemistry often use different units for the same quantity. For example, in theUnited States speed limits are given as miles per hour; in many other countries speed limits aregiven as kilometers per hour.LEARNINGOBJECTIVESIdentify the units used to measure physical quantitiesBecome familiar with the prefixes used for larger and smaller quantitiesMaster the use of unit conversion in solving problemsSUCCESSCRITERIAAssociate units with physical quantitiesReplace prefixes by multiplying by appropriate numerical factorsIdentify, set up, compute, and validate unit conversionsPREREQUISITEExponential notationMODEL1:INTERNATIONALSYSTEMOFUNITS(SI UNITS)Table 1Physical QuantityName of UnitAbbreviationmasskilogramkglengthmetermtimesecondstemperatureKelvinKelectrical currentampereAamount of substancemolemol(continued on the following page)Units of MeasurementACTIVITY01-1
Chapter 1: Nature of Chemistry2Foundations of ChemistryMODEL1:INTERNATIONALSYSTEMOFUNITS(SI UNITS),CONTINUEDTable 2PrefixAbbreviationMeaningteraT1012gigaG109megaM106kilok103centic10–2millim10–3microμ10–6nanon10–9picop10–12femtof10–15ExamplesMass: A quarter-pound hamburger has a mass of 0.11 kg.0.11 kg = 110 gLength: A tall basketball player (7 feet) has a height of 2.15 m.2.15 m = 215 cm = 2150 mmTime: There are 3300 s in a 55 minute chemistry lecture.3300 s = 3.300 ksTemperature: Water freezes at 273 K.1×103g = 1000 g = 1 kg1 cm = 0.01 m = 1×10–2m10 cm×10 cm×10 cm = 1000 cm3= 1 L(Note: L = liter)1 ps = 1×10–12sKEYQUESTIONS1.What are the 6 basic units and their abbreviations listed inModel 1(Table 1)? (You need to havethese units and their abbreviations memorized. Writing them without looking at the table will helpyou remember.)2.What are the 10 prefixes listed inModel 1(Table 2), along with their abbreviations and meanings?

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