CHAPTER 1 & 2 Chemistry Matter & Change

CHEMISTRY STUDY OF COMPOSITION AND BEHAVIOR OF MATTER Organic Chemistry: Inorganic Chemistry: Analytical Chemistry : Physical Chemistry : Biochemistry: Study of carbon compounds Study of non carbon compounds Study of composition of substances Study of behavior of substances Study of the chemistry of living things “What stuff is made of and how it acts”

How Chemistry is Used Pure Chemistry: Knowledge for knowledge’s sake. Research to learn how something works. May lead to and application. Ex: Research for synthetic rubber 1940’s o Applied Chemistry Research directed to a specific goal or application. Ex: Silly Putty 1950’s

Scientific Method Systematic problem solving approach Observations Noticing a problem (car won’t start) Hypothesis (battery dead) Possible explanation Experiment Procedure used to test the hypothesis (jump start?)  Manipulated Variable – Independent Variable Variable you change during an experiment.  Responding Variable- Dependent Variable Variable you observe during the experiment

Scientific Method Continued THEORY: LAW: Tested model that explains WHY an experiment gives certain results. Ex: Atomic Theory Statement that summarizes the results of many observations and experiments. Can be proven and usually is an equation. Ex: Law of Gravity (objects fall at a rate of 9.8 meters per second) Model of atom has changed over time.

PROPERTIES OF MATTER MATTER: WEIGHT: MASS: VOLUME: Anything that has mass and takes up space Amount of substance and object contains Earth’s attraction for an object Amount of space an object takes up GRAVITY

PHYSICAL PROPERTY QUALITY OF A SUBSTANCE that can be analyzed without changing the composition of the substance, Ex: color, odor, density, MP, BP, conductivity CHEMICAL PROPERTY ability of a substance to undergo a chemical reaction and form new substances Ex: sodium explodes in water, iron nail rusts, wood burns

Changes in Matter Physical Change: Change in a substance that does not change composition. Same substance in the beginning and end. Ex: cutting, grinding, tearing, painting, phase change

Chemical Change Change in the composition of a substance. Different substance in the end. Ex: burning, rusting, chemical reactions

Demo: SUGAR + WATER C 12 H 22 O 11 + H 2 O  C 12 H 22 O 11 + H 2 O REACTANTS YIELD PRODUCTS STARTING AND ENDING MATERIALS ARE THE SAME: PHYSICAL CHANGE DEMO: SUGAR + SULFURIC ACID C 12 H 22 O 11 + H 2 SO 4  12 C + SO H 2 O REACTANTS YIELD PRODUCTS STARTING AND ENDING MATERIALS ARE DIFFERENT: CHEMICAL CHANGE

INDICATORS OF A CHEMICAL CHANGE COLOR CHANGE ODOR CHANGE ENERGY CHANGE FORMATION OF A GAS NOT EASILY REVERSED FORMATION OF A PRECIPITATE- (solid formed from 2 aqueous solutions)

What’s happening during a chemical reaction? Only the OUTER SHELL ELECTRONS called (Valence Electrons) of atoms are involved. atomsCombine, break away or rearrange Law of Conservation of Mass Matter is not created or destroyed. Mass reactants = Mass of products

Energy Changes Both physical and chemical changes involve energy changes Types of energy include heat, light, bond energy ENDOTHERMIC EXOTHERMIC Law of Conservation of Energy Energy is not created or destroyed. Energy of reactants = Energy of products Needs or requires energy (heat), takes heat in, surroundings feel cooler Gives off or releases energy (heat), gives off heat, feels warmer. Energy is a (REACTANT) Energy is a (PRODUCT)

States of Matter solid liquid gas Density Movement shape volume D = mass/volume Packed very close together, incompressible Vibrate in place definite Packed close together, incompressible Very far apart (99%empty space), compressible Slide past each other Rapid, random straight line indefinite definiteindefinite

Phase Changes SOLID  ==========  LIQUID  ===========  GAS MELTINGBOILING FREEZINGCONDENSATION HEAT OUT (EXOTHERMIC) HEAT IN (ENDOTHERMIC) H 2 O: ICE WATER * WATER VAPOR *The term VAPOR is used when a substance that is normally a liquid or solid at room temperature is in a gaseous state.

Types of Matter Substance Mixture (homogeneous) (_________________________)(______________________) (______________________) Element Compound Homogeneous Heterogeneous (_______________________) Element _____________________ Homogeneous (______________________) ___________________________________________________________ Compound ____________________ Heterogeneous _________________ ______________________________ _____________________________ (_____________________________) _____________________________ Definite compositionVariable composition Separated physically Separated chemically One kind of atom Found on periodic table, H, He Chemical blend of 2 or more elements H 2 O, NaCl, BaSO 4 solution; one phase Same throughout; koolaid, jello Not the same throughout; different phases Chunky soup, salad, soil

Comparison of Compound VS Mixture Compound Mixture 1. Chemically combinedPhysically combined 2. Can only be separated byCan be separated chemical means.physically. 3.Components are present in aComponents may be definite proportion by weight present in any proportion 4.Compound has different Components in mixture properties than its individual keep their original components.properties.

Chemical Symbols - Every element has a symbol - Symbol consists of 1 or 2 letters, first is capitalized -Some named for Greek and Latin names - Ex: Sodium (Natrium) – Na; Iron (Ferrous) Fe - Chemical Formulas Combination of elements to represent compounds. Ex: C 12 H 22 O 11 sugar; H 2 O water

Reaction symbols solid (s) * liquid (l) * The following are the only liquids used during a chemical reaction Water, Bromine & Mercury Everything else in a liquid state is an Aqueous Solution ( ) gas as a product (g) gas Solid product formed from 2 aqueous solutions precipitate( ) or (ppt.) aqueous(aq) Dissolved in water.