# Unit 1

 Scientific Method ObservationQuestionsHypothesisDataConclustionResults Hypothesis A tentative explanation based on observations Experiment An observation of natural phenomena carried out in a controlled manner so that the results can be duplicated Law States a measurable relationship Theory Tested explanation of basic natural phenomena Mass the quantity of matter in a material Matter occupies space Law of Conservation of Mass Matter can neither be created nor destroyed during a normal chemical reaction. What is the difference between mass and weight? Weight depends on gravity Solids Have a fixed shape and fixed volume Liquids Have a fixed volue but not a fixed shape Gases Do not have a fixed volume or shape Physical change A change in which the chemical composition of the sample does not change Chemical change A change in which the chemical composition of the sample changes. (new matter) Physical properties characteristics of a material that can be observed without changing the substance (its chemical identity) appearancedensity Chemical Properties characteristic of a material which is evident when the material undergoes a chemical change. reactivitytoxicity Elements a pure substance that cannot be broken down any further by chemical means. oxygen, mercury, sulfur Compounds A combination of more than one element that can be broken down further by chemical reations. Heterogeneous mixtures a mixture in which the properties vary within a sample Homogeneous mixture a mixture in which the properties are constant throughout the sample. Precision How close the measurements are to one another Accuracy Closeness of a measurement ot its true value Uncertainty measurements cannot be exact Significant figues digits in a mesurement that include all certain digits plus a finial digit with some uncertainty. Rules to significant digits non-zero significantconfined zeros significantleading zeros not significanttrailing zeros significant with decimal Rounding if next digit is >5 round upif next digit is <5 round downif next digit is =5 round to nearest even number Adding and Subtracting Sig Figs Last common place that each number hasRound answer to place of least sig fig Multiplying and Dividing with Sig Figs Look at the number of sig fig in all values; report the fewest number of sig fig in answer Scientific Notation exponential notation where there is exactly one non-zero digit the the left of the decimal positive  <-  decimal  ->  negative Base units of metric system length -> meter -> mmass -> gram -> gvolume -> liter -> Ltime -> second -> s Measurement staircase and rules tera, giga, mega, kilo    basedeci, centi, milli, micro, nano, pico up stair divide by 10, down stair multiply by 10 Celsius/Fahrenheit Conversion Tf = (9/5) Tc + 32.000 F Celsius/Kelvin Conversion Tk = Tc + 273.15 Volume Length * Width * Height Density Mass / Volume g / mL Common conversions with liters 1 L = 1 m31 mL = 1 cm3 Authoratcannon ID173956 Card SetUnit 1 DescriptionChemistry and Measurement Updated2012-09-28T00:38:18Z Show Answers