1 Chapter 3 Matter Properties and Changes key Terms matter, States of matter, Properties, physical properties, intensive and extensive physical change, phase change, chemical property, chemical change/reaction law of conservation of mass heterogeneous & homogeneous mixture, solution Solute, solvent, aqueous solution, alloy Distillation, chromatography, filtration etc. substance, compound, element, Law of definite proportions Law of multiple proportions

2 Chemistry is the science that investigates and explains the structure and properties of matter. Matter is anything that has mass and occupies space.

3 States of Matter Which has definite shape, definite volume??? Which flows, is easily compressible????

4 Physical Property of a substance can be observed or measured without changing the substance’s composition. There are two types: Extensive Properties are dependent on amount (ex: mass, volume) Intensive Properties are independent of amount and can be used to identify a substance. Examples: color, odor (scent), hardness, boiling point, melting point, density...

5 Chemical Property is the ability or inability of a substance to undergo a chemical reaction The ability to… Example:iron + sulfur  iron sulfide iron + oxygen  rust Food spoilage, decomposition, rotting, combustion, oxidation, corrosion Name chemical and physical properties of copper

6 Physical Changes alters a substance without changing chemical composition Examples: phase changes (boiling, freezing, evaporating) breaking, splitting, cutting, crushing...

7 Chemical Change or Chemical Reaction Change of a substance into one or more new substances. Evidence of chemical change is a change in properties, such as changes in color, odor (think food spoilage), and always involves energy change.

Law of conservation of mass In a chemical reaction mass is neither created nor destroyed. The sum of masses of all reactants is equal to the sum of masses of all products. Mass is conserved in any physical or chemical change. Mass (reactants) = Mass (products) 16g oxygen + ???g hydrogen  18g H 2 O

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10 Mixtures A mixture is a variable combination of two or more substances, each substance retains its own chemical properties. The substances can be separated by physical methods.A mixture is a variable combination of two or more substances, each substance retains its own chemical properties. The substances can be separated by physical methods. Heterogeneous mixtures are not uniform in composition.Heterogeneous mixtures are not uniform in composition. Homogeneous mixtures, also called solutions, have uniform properties throughout.Homogeneous mixtures, also called solutions, have uniform properties throughout. Opaque liquids

11 Examples of homogeneous mixtures Alloys are solid solutions that contain different metals (brass, steel, bronze etc.). Aqueous solution is a homogeneous mixture where water is the solvent. Example sugar water: Sugar is the solute Water is the solvent

12 Classify the following mixtures as either homogeneous or heterogeneous  motor oil  clear nail polish  granite  glass  air  chocolate-chip ice cream  brass (blend of copper and zinc)

13 Distillation Examples of methods to separate mixtures Filtration Evaporation Distillation Chromatography Crystallization Sieving Physical methods Use differences in physical properties to separate the substances in a mixture

14 Elements and Compounds Pure substance contains only one type of matter and is either a compound or element An Element is made from one type of atoms, All elements are organized in the periodic table A Compound is made from more than one type of atoms. Compounds can be separated into simpler substances only by chemical means. Elements are always present in the same ratio in a given compound. Properties of a compound are different from those of the elements composing it.

15 The Law of Definite Proportions states that a compound is always composed of the same elements in the same proportions by mass, no matter how large or small the sample. The relative amounts of the elements in a compound can be expressed as percent by mass, Percent by mass (%) = mass of element x 100% mass of compound

16 The Law of Multiple Proportions states that when different compounds are formed by a combination of the same elements, different masses of one element combine with the same fixed mass of the other element in a ratio of small whole numbers. John Dalton Mass ratio [mass A/mass B] of compound 1 = small whole number Mass ratio [mass A/mass B] of compound 2

17 Example: different compounds made from oxygen and nitrogen

18 Classify the following as element or compound þ water  gold  diamond þ ammonia  mercury  carbon dioxide Name the chemical symbol for þCarbon  Oxygen  Hydrogen  Sodium  Chlorine  Nitrogen

19 Mixture, compound or element?  motor oil  sugar  salad dressing  chlorine  air  salt water  diamond  glass  hydrogen peroxide

20 Example MixtureCompoundExample Sugar waterwater (H 2 O) separated Physical byChemical methods into Example Substances Elements Example water and sugaroxygen, hydrogen