I. Measurements A) SI units —international system of units. (metric system)SI units 1) Quantity a) Length Metric Measurements used in class Meter (m) prefixes are added to meter such as centimeter or millimeter. If it is a centimeter does it still length? What is the centi representing then?

b) Mass Measurement used in class Grams (g) prefixes are added like kilograms or milligrams c) Volume Measurement used in class Liters (L) prefixes are added like milliliters

More SI Units in metric system 1.Seconds: standard for time measurements. 2.Newton: standard for force

Check for understanding What is the metric unit used to measure mass? Grams What is the metric unit used to measure length? Meters What is the metric unit used to measure volume? Liters

Metric Prefixes Conversion factorPrefixSymbolExponential notation 1Megameter=1,000,000 meterMega-M Kilometer= 1000 metersKilo-K Hectometer= 100 metersHecto-H Dekameter= 10 metersDeka-D meter= 10 decimetersdeci-d meter= 100 centimeterscenti-c micrometer=10 -6 Microμ10 -6 The word meter can be replaced with liter or gram when using the metric prefixes

Representing Measurements as Data Measurements are a form of data and can be represented in tables, graphs, charts --A good graph, table, or chart is properly labeled (ACT loves charts, graphs, tables)

B) Reliability of Measurements 1)Accuracy—how close measured values are to the accepted value or target 2)Precision—how close a series of measurements are to one another

3) Significant Figures a)No measuring device can give perfect measurements. b)The last digit given is uncertain or a guess. For example: a balance determines the mass to be 3.6 grams. The 6 is the uncertain number. It could be really be 5 or 7.

II. Scientific Notation A)Chemistry deals with numbers very large and small Ex: mole=602,000,000,000,000,000,000,000 Carbon atom = cm B) Scientific notation uses powers of ten to make using very large or small numbers easier6.02 x and 2 x 10 -9

C) How to Use Scientific Notation 1) numbers larger than 1 will receive positive exponent or moving decimal left creates positive exponent Ex: 12,000, X ) numbers smaller than 1 will receive negative exponent remember or moving decimal right creates negative exponent Ex: X 10 -7

3) To write numbers in scientific notation the decimal must be moved until it would leave ONE number to the left of decimal 340, x x LeftRightLeftRight

D) Getting out of Scientific Notation 1) Positive exponents mean numbers larger than one, meaning you must move decimal to right 2) Move decimal to right equal to exponent 2.1 x ,000,000 3) Negative exponents mean numbers smaller than one, meaning you most move decimal to left 4) Move decimal to left equal to exponent 1.9 x