Key Terms Chapter 3 MatterUnits MeterLiter KilogramSI MassBalance WeightScientific Notation Significant FiguresDensity VolumeNewtons 1

Chapter 3 MEASUREMENT OF MATTER 2

Matter  Anything that takes up space and has mass  2 components: mass and volume  Every object has mass and volume  Matter must be described, so we use measurements to describe it 3

Units and Work  A measurement without a unit is useless!!!  The most precise info can be communicated with numerical/quantitative data  Units will be required with any quantitative answer  Grading deduction if no units  Grading deduction if no work shown 4

Metric Units  Why do we need a standard for measurements?  They were based on changeable standards  There were too many different units  Conversion from one unit to another can be difficult 5

International System (SI)  All units are related by multiples of 10  Simplifies and standardizes all data  Mass is measured in kilograms (kg)  Volume is measured in liters (L)  Distance is measured in meters (m) 6

Prefixes  Developed a system of prefixes to modify the units to apply them to other situations  Prefixes mean a certain amount of the original unit  Kilo = 1000  Deci =.1  Milli =.001 7

Metric Prefixes 8 Mega10 6 M Kilo10 3 k Hecto10 2 h Deka10 1 da Unit10 0 Deci10 -1 d Centi10 -2 c Milli10 -3 m Micro10 -6 µ

Unit conversions Convert the following: 50 kilometers to meters 2,000,000 micrometers to Megameters 49 decimeters to millimeters 280 meters to hectometers 4 Megameters to kilometers 307,840 inches to miles 100 feet to centimeters 9 Mega10 6 M Kilo10 3 k Hecto10 2 h Deka10 1 da Unit10 0 Deci10 -1 d Centi10 -2 c Milli10 -3 m Micro10 -6 µ

Review  Review: Convert 4,593,500 cm into km What is the unit of volume in the metric system? Liter What is the unit of mass in the metric system? Kilogram What is the unit of length in the metric system? Meter 10

Significant Figures What is the importance of significant figures? Used to tell how accurate a measurement is More significant figures = more precise measurement 11

Significant Figures Calculating Significant figures Rules for Significant Figures Atlantic-Pacific Rule 12

Significant Figure Rules  All non-zero numbers are significant ( has 5 SF’s)  All zeros between non-zeros are significant (208.5 has 4 SF’s)  All zeros with decimal points are significant except leading zeros has 4 SF’s; has 3 SF’s (the zeros are just place holders) 13

Significant Figure Rules  Trailing zeros with no decimal are NOT significant (5300 has 2 SF’s)  Trailing zeros with a decimal point ARE significant (530.0 has 4 SF’s)  The number of significant figures is not always the same as the number of digits in the number 14

Significant Figures 214 – has 3 digits and 3 significant figures 210 – has 3 digits but only 2 significant figures How many significant figures in these numbers?

Significant Figures  Atlantic-Pacific Rule 46,

Significant Figures  When multiplying and dividing, the answer can have no more significant figures as the number with the least amount in the equation Ex. 2 cm X 4.55 = 9.10 cm 2 = 9 cm 2  When adding and subtracting, the answer may be no more precise than the least precise number in the equation 30 g g = 52.5 g = 50 g 17

Significant Figures x ÷ – x ÷

Rounding  When rounding: Round numbers 4 and lower, down Round numbers 5 and higher, up Round these numbers to 3 significant figures

Measuring Matter  Mass: amount of matter in an object  Measured using a balance (kg)  Weight: measure of force of gravity on object  Measured using a spring scale  Force is measured in Newtons (N)  Law of Mass Conservation In all chemical and physical changes, matter is neither created nor destroyed 20

Volume  Anything that takes up space  3 dimensions: length, width, height  Measured in Liters (L)  To find volume, multiply the length, width, and height 21

Measuring Volume Regular solid: length x width x height Graduated cylinders Measure volume of liquids Meniscus: curved part of the liquid in the cylinder Measure at the lowest point of the meniscus Water Displacement Method: measure irregular shaped objects Measure original height of liquid Measure new height after inserting object into water Difference is the volume of the irregular object 22

Density  The amount of mass in each unit of volume d = m/v Liquids are measured in g/cm 3 23

Density  Find the density:  V = 50 cm 3  M = 2000 g  D = 40 g/cm 3 24

Density  If a chunk of lead is displaced 36.0 cm 3 (mL) of water and had a mass of 407 grams, what would its density be? d=m/v V= 36.0 cm 3 Mass = 407 g  D = 11.3 g/cm 3 25

Scientific Notation  Science sometimes involves numbers that are either very large or very small  The mass of the earth is believed to be 5,980,000,000,000,000,000,000,000 kg  The mass of a hydrogen atom is kg  It is more convenient to write these numbers in scientific notation 26

Scientific Notation  Written as the product of a number between 1 and 10 and a power of 10  The mass of the earth would thus be written 5.98 x  The mass of a hydrogen atom would be written 1.67 x

Scientific Notation  5,600,000,000   x 10 2  x  x