Chemistry the study of matter and the changes it undergoes sodiumchlorine sodium chloride

Scientific Method 1.Make observations 2.Formulate hypotheses 3.Perform experiments Benzene Ring

Units of Measurements in SI Units Physical QuantityName of UnitAbbreviation Masskilogramkg Lengthmeterm Timeseconds Amount of Substance Molemol TemperaturekelvinK

Prefixes PrefixSymbolValue gigaG10 9 megaM10 6 kilok decid10 -1 centic10 -2 millim10 -3 micro μ nanon10 -9 picop10 -12

How to use prefixes Convert mg to grams.

How to use prefixes Convert 700. nm to meters.

Convert 8905 grams to kilograms.

Uncertainty in Measurement 1)20.15 mL 2)20.14 mL 3)20.16 mL 4)20.17 mL 5)20.16 mL uncertain digit certain digits

Significant figures automatically indicate the uncertainty in a measurement mL4 significant figures The last digit is usually assumes to be

Another way to write uncertainty

All measurements have some degree of uncertainty!

In analyzing a soil sample, a soil scientist measures g sample. Later the scientist uses a scale which measures 15 g. What is the difference between the measurements g and 15 g?

15.00 g –M–Means –M–Measurement is between g and g. 15 g –M–Means –M–Measurement is between 14 g and 16 g

Precision & Accuracy Not precise Not accurate

Precise Not accurate

Precise & accurate!

1)20.15 mL 2)20.14 mL 3)20.16 mL 4)20.17 mL 5)20.16 mL Precise Measurements

Accuracy The agreement of a particular value with the true value. Precision The degree of agreement among several measurements of the same quantity

Significant Figure Review 1.Nonzero integers always count as sig figs

Sig Fig Review 2.Leading Zeros Zeros that precede nonzero digits do not count as sig figs

Sig Fig Review 3.Captive Zeros Zeros that are between nonzero digits always count as sig figs

Sig Fig Review 4.Trailing Zeros Zeros at the right end of a number are significant if there is a decimal present x 10 2

Atlantic Pacific Rule

Sig Fig Review 5.Exact Numbers If a measuring device was not used, then the number is an exact number. Counting: 10 apples Defined Quantities: 1 inch = 2.54 cm Numbers in Formulas: 2 πr (The 2)

Sig Figs & Calculations 1.Multiplication & Division Round to the least precise measurement used in the calculation x 1.5 =

Sig Figs & Calculations 2.Addition & Subtraction The result has the same number of decimal places as the least precise measuremnt =

Rules for Rounding 1.In a series of calculations, carry the extra digits through to the final result, then round.

Rules for Rounding 2.When you round, –i–if the digit to the right of the final sig fig is less than 5, then the preceding digit stays the same –I–If the digits is equal to or greater than 5, then the preceding digit should be increased by

Dimensional Analysis or

Unit Conversions A glass rod is 6.00 inches long. What is the length in centimeters? Unit Factor

Temperature º C to KK = º C K to º C º C = K – 273 º C to º F º F = 1.8 º C + 32 º F to º C º C =

Density – a derived unit

Units for Density g/cm 3 g cm -3 g/L

Classification of Matter Matter Heterogeneous Mixtures Homogeneous Mixtures Pure substances CompoundsElements Atoms Nucleus Electrons protonsneutrons quarks

States of Matter Solid Definite shape & volume particles vibrate around fixed positions

Liquid Take the shape of the container Definite volume Particles are free to move

Gas No definite shape No definite volume