MeasurementEnglish, SI, and Metric Systems

English System• This is the system we use on a day-to-day

basis.• The U.S. adopted the metric system in 1866. • The U.S. has not prohibited the use of

“English” units in everyday life (i.e. construction, real estate, retail, and education.)

• The U.S. has not made the crucial transition from "soft metric" to "hard metric", so that "1 pint (473 mL)" becomes "500 mL (1.057 pint)", with the traditional equivalent fading into smaller type sizes and finally disappearing.

Metric System• Designed during the French Revolution of the

1790's• Brought a uniform measuring system to Europe• U. S. adopted its use in 1866 but has never

fully converted to it.• Merchants, scientists, and educated people

throughout Europe realized that a uniform system was needed, but it was only in the climate of a complete political upheaval that such a radical change could actually be considered.

SI System• Revised version of the metric system adopted

in 1960• Système International d'Unités, abbreviated as

SI • Contains seven base units• All other units are calculated or derived from

the basic seven.: length (meter), mass (kilogram), time (second), temperature (Kelvin), amount of substance (mole), electric current (ampere), luminous intensity (candela)

SI Base UnitsQuantity Unit Symbol

Length meter m

Mass kilogram kg

Time second s

Temperature Kelvin K

Amount of substance

mole mol

Electric current ampere A

Luminous intensity

candela cd

Common Measurement Quantities

• Length – The distance from one place to another

• Mass – The amount of matter in an object

• Time – The measure of the duration of an event

• Temperature – The measure of the average speed of the particles that make up a material

• Volume – The amount of space an object takes up

Measurement UnitsQuantity English Metric SI

Length Foot Meter Meter

Mass Pound** Gram Kilogram

Time Second Second Second

Temperature Fahrenheit Celsius Kelvin

Volume Gallon Liter Meter3

** Note: Pound is the English unit for weight. The seldom used slug is the English unit for mass.

Length• Unit name: meter• Unit abbreviation: m

Length• For reference, 1 meter is a little longer than 1

yard or 3 feet. It is about half the height of a very tall adult. A centimeter is nearly the diameter of a dime, a little less than half an inch. A millimeter is about the thickness of a dime.

Length Tools• Large – odometer• Medium – meter stick• Small – ruler• Very tiny – Vernier caliper

Mass• Unit name: kilogram

• Unit abbreviation: kg

Mass• For reference, 1 gram is about the mass of

a paper clip. One kilogram is about the mass of a liter of water.

Mass Tools• Triple beam balance

• Electronic balance

Time• Unit name: second

• Unit abbreviation: s

Time• Technical definition: The time needed for a

cesium-133 atom to perform 9,192,631,770 complete oscillations.

• In practice, every 3 calendar years will have 365 days, and every 4th year is a "leap year", which has 366 days, to make up for the extra quarter day over 4 years. The years 2008, 2012, and 2016 are all leap years. This gives us a total of 52 complete 7 day weeks in each calendar year, with 1 day left over (or 2 in a leap year).

Time Conversions

• 1 minute = 60 seconds1 hour = 60 minutes = 3600 seconds1 day = 24 hours1 week = 7 days1 year = 365.25 days (for the Earth to travel once around the sun)

Temperature• SI Unit name: Kelvin

• Unit abbreviation: K

• Metric name: Celsius

• Metric abbreviation: °C

Temperature• In lab, we will use Celsius thermometers.

• Temperatures must be converted to Kelvin when doing gas law problems.

• Ice forms at 0°C and water boils at 100°C.

• We will discuss temperature conversions during the gas law unit.

Amount of substance

• Unit name: mole

• Unit abbreviation: mol

THE MOLE• Chemistry unit used to describe the

amount of a substance.• We use it to describe amounts of

very small things like atoms.• It is a counting unit, sort of like a

dozen. (1 dozen = 12)• The mole is equal to 6.022 x 1023

particles.

MOLE DAY• Celebrated on October 23rd from 6:02 am to 6:02 pm

• Celebrates Avogadro’s number: 6.022 x 1023

• http://www.moleday.org/

Electric current• Unit name: ampere

• Unit abbreviation: A

Luminous Intensity• Unit name: candela

• Unit abbreviation: cd

SI Units You Need to Know

• You will need to know the SI units for length, mass, time, temperature, and amount of substance.

• Electric current and luminous intensity are physics units; therefore, you will not need to know these for the test.

Derived Units

• From the 7 base units, all other units of measure can be determined using mathematical equations.

• These units include area, volume, and density.

Area, Volume, & Density• Area = length x length• Area = m x m = m2

• Volume = length x length x length

• Volume = m x m x m = m3

• Density = mass / volume

• Density = kg / m3

Volume Tools• Liquid – graduated cylinder• Rectangular solid = length x width x height• Irregular solid – water displacement

Density• Amount of matter (mass) contained in a

unit volume

• Density is calculated by dividing the mass by the volume.

Material Density (g/mL)

Water 1.000

Ice 0.917

Air 0.00119

Gold 19.31

Density Tools• Equation Density = mass/volume• Units: g/mL