Scientific method Method for answering questions Make an observation Ask a question (hypothesis) Obtain facts (experiment) Explain experiment (conclusion) Theory or law

Measurements – SI units QuantityNameUnit LengthMeterM MassKilogram (gram) Kg (g) TimeSecondS (sec) TemperatureKelvinK AmountMole

Metric prefixes PrefixAbbrevfactor KiloK10 3 Decid10 -1 (1/10) Centic10 -2 (1/100) Millim10 -3 (1/1000) Micro10 -6 (1/1,000,000) Nanon10 -9 (1/1,000,000,000)

Derived units  Area  L x w  Volume  L x w h For more see appendix p 806 Agenda p R-11

Reliability  Precision ability to repeat measurement  Accuracy ability to get accepted value  Bulls eye

Uncertainty in Measurement  Measurements involve estimation in last digit  Remember …..

Significant digits  The certain and 1 estimated digit of a measurement  Atlantic-Pacific rule if a decimal is Absent, count first non- zero number from Atlantic side if a decimal is Present, count first non-zero number from the Pacific side

Practice How many significant figures in each?

Calculations  Addition/subtraction count least places after the decimal  Multiplication/division count the least number of significant digit

Practice Calculations x = = = 4. (3.2 x 10 3 )(6.003 x )= x 10 6 = 5.1 x 10 -9

Problem Solving  1.Write known and unknown  2.Write equation  3.Use factor label method (start with the units of the known)  4.Calculate  5. Circle answer with correct significant figures

Ratios Speed Distance time Density mass volume

Ratios of equal terms 1 m = 10 dm 1m10 dm 10 dm 1m 1 min = 60 sec 1 min60 sec 60 sec1 min For more see agenda p R-10

Factor label=Dimensional Analysis Using units to solve problems Show work using units 1. How many seconds in 14 days? Show work. 2.How many mL in 1.09 kL? 3.Convert 3.4 g/ml to dg/cL

Graphs  Create a good data table

Computer Graphing  Excel  A- x axis,flask size (ml)  B- Y axis, time (sec)  Highlight all 2columns  Chart Wizard  X,Y scatter middle chart, left column  Title (include your name), label both axis  New sheet  Unshade background  Print 1 to science dept

Excel A- x axis (volume), B- Y axis (mass)  Highlight all 2columns, Chart Wizard  X,Y scatter top chart, left column  Title (include your name), label both axis  New sheet  Chart add trend line Linear  options tab Check off  intercept=0  display equation chart,  Unshade background/format plot area/white box  Print to lexchex or sci dept

Slope Rise = y 2 -y 1 = m 2 -m 1 = mass Run x 2 -x 1 v 2 -v 1 volume Pick 2 points on the line. Write the coordinates (x 1,y 1 )(x 2,y 2 ) Calculate the density Do this on your graph.

Pure Matter Elements cannot be broken down by chemical processes Compound Chemical combination of elements (share or transfer of electrons)

States of Matter  Gas  Liquid  Solid  Plasma

What’s the Difference? Solids are orderedLiquids have Some order Gases are almost random

Matter Anything that has mass and volume do not copy in notebook Density Pressure Container Solid High not affectedown shape Liquid High not affected takes shape Gas low affectedfills Plasma low affected fills

Changes in Matter  Physical changes Involve no change in composition P hysical properties: Boiling/melting point, density, color, odor, ductile  Chemical changes  Involves a change in composition Heat change Color change Gas evolved Precipitate formed Chemical properties: combustion, reactivi ty

Changes of State  What is happening to the molecules as ice heats up? Change from one state to another takes energy  Is the melting point and freezing point the same?  Heat of fusion  Is the evaporation and condensation pt the same?  Heat of evaporation  What is the difference between steamed and boiled?

Cooling Curve Liquid Solid Gas Condense/evaporate Freeze/melt

Temperature Scales  Fahrenheit was a thermometer maker He was a very good thermometer maker Why do we still use his scale?  Celsius is based on the melting point and boiling point of water 0 o C = Freezing point of Swiss Alps snow 100 o C = Boiling point at sea level Why does it have to be at sea level? Why is this better than Fahrenheit?