INTRODUCTION

CHEMISTRY The science that deals with the materials of the universe and the changes that these materials undergo Wood burns Plants grow Iron rusts Bread bakes Human digestion

The Scientific Method State the problem Make observations Form a hypothesis Perform an experiment Develop a Law A summary of observed behavior Develop a theory An explanation of behavior Continue to experiment Modify theory as needed

Important Terms Matter Mass Volume Qualitative observations Anything that has mass and volume Mass Amount of matter in an object Volume Amount of space an object occupies Qualitative observations Observations not requiring measurements Quantitative observations Observations requiring measurements

Classification of matter has mass and volume PURE SUBSTANCES Can write chemical formula ELEMENT One type of atom COMPOUND Two or more different atoms chemically bonded MIXTURES Variable ratio HOMOGENEOUS solutions HETEROGENEOUS Colloids and suspensions

Energy All objects possess energy An object has two general forms of energy Potential energy The energy of an object due to its position Kinetic energy The energy possessed by an object due to its motion Law of conservation of energy Energy is neither created or destroyed Energy can be converted from one form to another

PHASES OF MATTER Solid Liquid Gas Definite volume and shape Definite volume but takes shape of container Gas No definite volume and no definite shape

Physical and Chemical Properties and Changes Physical Property Characteristics that describe a substance Physical Change A change that does not affect the composition of the substance Chemical Property Characteristics that refer to the ability to form new substances Chemical Change A change which produces new substances

Measurements

SIGNIFICANT FIGURES The reliable digits in a measurement based on the measuring instrument Atlantic-Pacific Method A = decimal Absent, begin counting from right P = decimal Present, begin counting from left

TRY THESE 1,000 1 sig fig 0.001 0.0010 2 sig fig 1000.0 5 sig fig

Rules for Using Sig Figs Multiplication/Division The number of sig figs in the result is the same as that in the measurement with the smallest number of sig figs 4.56 x 1.4 = 6.384 or 6.4 8.315/298 = 0.0279027 or 0.0279 Addition/Subtraction The limiting term is the one with the smallest number of decimal places 12.11 + 18.0 + 1.013 = 31.123 or 31.1

where 1.00 ≥ M < 10 and n is an integer SCIENTIFIC NOTATION The expression of numbers in terms of M x 10n where 1.00 ≥ M < 10 and n is an integer

TRY THESE 25,000 2.5 X 104 0.00468 4.68 X 10-3 0.0100 1.00 X 10-2

ACCURACY/PRECISION Accuracy Precision How close a measurement is to the actual value Precision How close a set of measurements are to each other

Dartboard analogy

DENSITY Mass Volume Density Amount of matter in an object Volume Amount of space an object occupies Density Mass per unit volume Percent Error = /actual-experimental/ x 100 actual

Formula for density What is the density of an object with a mass of 7.65 g and a volume of 4.5 mL?

Factor Labeling/Dimensional Analysis 1 in = 2.54 cm 5280 ft = 1 mi Convert 3.1 miles to kilometers

1 kg = 2.2 lbs Convert 3.3 lbs to grams

Convert 8.00 km to miles

CHEMICAL REACTIONS Chemical Reaction Reactant Product A change in which one or more substances are changed into one or more new substances Reactant A starting substance in a chemical reaction Product A substance produced as the result of a chemical change