Units of MeasurementMeasurements are

quantitative information. They include numbers AND

units.

Measurements Represent Quantities

Quantity = has magnitude, size, or amount

Quantity ≠ measurement! Ex. The quantity, volume, is

represented by measurements reported in units like teaspoons, milliliters, cubic centimeters, gallons, quarts, etc.

Standards Agreed upon measurement of a

quantity• Ex. The foot

SI Measurement (AKA. The metric system)

Scientists worldwide use the metric system of measurement

SI has 7 base units (see table 1 and KNOW these quantities, units, and abbreviations)

NEVER use commas when writing numbers (too easily confused with decimals)

Length (l) meter (m)Mass (m) kilogram (kg)Time (t) second (s)Temperature (T) Kelvin (K)Amt. of a substance (n) mole (mol)Electric current (I) ampere (A)Luminous intensity (Iv) candela (cd)

Quantity Unit

Mass Measure of the amount of matter

(stuff) Does NOT change with location

Weight DOES change depending on gravity

I weigh less on the moon, but my mass does NOT differ from my mass on Earth.

Metric Prefixes Prefixes added to base units are used

to represent quantities larger or smaller than the base unit.

Ex. 1 centimeter is 1/100th of a meter1 cm = 0.01 mOR 1 cm = 1 X 10-2

Table 2 (pg. 35) KNOW THESE prefixes!!!!!!! Know the abbreviation for each prefix Know the conversion factor

(example) for each prefix Know that these prefixes can be

applied to ANY base unit

Conversion Factors A ratio (fraction) expressing the

equality btw two different units Can be used to convert from one unit

to the other

Ex. 4 quarters 12 inches 1 dollar 1 foot

Using Conversion Factors Express 17.5g in mg.

Express 45 km/hr in m/s.

This is called Dimensional Analysis

Derived Units Derived units are combinations of SI

base units

Area A l x w m2

Volume V l x w x h m3

Density D m/V kg/m3

Molar mass M m/amt kg/mol Molar volume Vm V/amt

m3/mol Energy E force x length joule (J)

Volume The amount of space occupied by

matter

Liquid volume is measured in liters (L)

1 L = 1000 cm3

1 mL = 1 cm3 (cubic centimeter or cc)

Density Ratio of mass to volume Amt of “stuff” / amt of space taken

by stuff

Density = how crowded the particles of matter are

Be sure to read about density and see table 4 on page 38!!!