Matter: Properties & Changes Chapter 3

3.1 Properties of Matter  Matter is very diverse—we must begin to organize and describe it. What is a substance? pure; has an unchanging composition Examples of a substance include… Examples of a substance include…

Watertable salt

& gasoline

What is not a substance?  Sea water Air

 What is a physical property?  A characteristic that can be observed/measured without changing the composition  Examples…

 Examples… shape, weight, color, density, odor, taste, hardness, melting/boiling point.  (If they have consistent composition= they have consistent phys property.)

2 types of phys properties Extensive property-  dependent on the amount of sub  Ex. Intensive property-  independent of the amount of sub  Ex.

Gold miners… gold vs. fools gold

 What is a chemical property?  Ability of a substance to combine with of change into one or more other substances.  Examples…

iron

 1. iron forming rust when combined with air.

 2. iron has no reaction with nitrogen gas.

 What are some physical properties of copper?  What are some chemical properties of copper?

What are some phys/chem properties of water?  Phys. prop.  Chem. prop.  Reacts with metals  Good solvent  pH

States of Matter

 Solid- will not conform to a container  Definite shape? yes  Definite volume? yes  Examples…  How are particles arranged? Tightly packed  Particle movement? No (very little)

States of Matter Liquids- matter that flows Definite shape? no Definite volume? yesExamples… How are particles arranged? They are less closely packed Particle movement? yes yes

States of Matter  Gases- matter that flows  Definite shape? no  Definite volume? no  Examples…  How are particles arranged? Very far apart  Particle movement? yes  Fills entire container? yes  Compressed? Very compressible

Gas versus Vapor GAS  Naturally gaseous Ex. Oxygen gas VAPOR  A gaseous STATE of a substance  Normally solid/liquid at room temperature  Ex. steam

3.2 Changes in Matter  Physical changes- changes that do not alter the composition of a substance.  Ex…

Physical changes  Keywords…  bend  grind  crush  Melt  freeze  boil  vaporize  condenses

 Chemical changes- one or more substances changes into other substances; aka CHEMICAL REACTION  Examples… HgO  Hg + O 2

Chemical change  Keywords…  Explodes  Rusts  Oxidizes  Corrodes  Tarnish  Ferment  Burn  Rot

Chemical change  Evidence of chem rxn… pg 63  color change  puts off heat  odor change  Solid is formed  Forms gases.

Conservation of mass  Conservation of mass-  Mass is neither created nor destroyed in any process, it is conserved. (Mass is recycled.)

Antoine Lavoisier  ( )

Conservation of Mass Mass reactants = Mass products Ex. HgO (s)  Hg (l) + O 2 (g) 216 g  200 g + ? 216 g  200 g + ? ReactantProducts (before rxn)(after rxn)

 Ex. In an experiment, g red mercury (II) oxide powder is heated in a test tube where it forms liquid mercury & oxygen gas g of liquid mercury was recovered. What is the mass of oxygen formed?  ** practice problems 6-9

3.3 Mixtures of Matter  What are two broad categories of matter?  Substance & mixtures  What is a mixture?  Combination of multiple sub

2 types of mixtures:  1. Heterogeneous mixture- (not blended smoothly)(can be sep. by phys. means)  Ex…  Sand & water  Ketchup  Oil & water  Others?

2 types of mixtures:  2. Homogeneous mixtures- (blended smoothly)(can be sep. by phys.means)  A.k.a. “Solutions”  Ex…

Ex… Type of solution Example: gas- gas gas- liquid liquid- gas liquid- liquid solid- liquid solid- solid

 List 4 ways to separate mixtures. 1. Filtration- separates solid from liquid Ex. 2. Distillation- sep. solution of 2 liquids b/c of different boiling pt. Ex. 3. Crystallization- sep of dissolved solid from solution Ex. 4.Chromatography- sep. components of a mixture by travelling Ex.

3.4 Elements & Compounds  What is an element?  A pure sub that cannot be further broken down  Ex… Na, N, Ca, O etc  What is a chemical symbol?  How many naturally occuring element are there?  91  H>Fr

3.4 Elements & Compounds  What was Dmitri Mendeleev’s most significant contribution to chemistry?  Chart that organized elements into rows & columns based on similarities.  Horizontal rows are called “periods”  Vertical rows are called “groups” or “family”  Elements of the same group have similar physical & chemical properties.

3.4 Elements & Compounds  What was so amazing about Mendeleev’s table?  He left blanks b/c he predicted that there were more elements that haven’t been discovered yet.

3.4 Elements & Compounds  What is a compound?  A substance consisting of 2 or more elements.  Ex… H 2 O, NaCl, CO 2  Compounds can be broken down by chemical means.

3.4 Elements & Compounds  Can water be decomposed?  Yes, electrolysis

 Are the properties of a compound the same as the elements of which it is composed?  NO  Ex.  Sodium- metal solid, soft, highly reactive with water  Chlorine- gas, yellowish, poisonous  Salt- crystal solid, hard, white, harmless

 Ex.  Oxygen- flammable, for respiration  Hydrogen- flammable  Water- not flammable

 What is the Law of Definite Proportion?  Regardless of mass, a comp. will always have the same proportion.  Formula for calculating percent by mass: mass of element X 100% = % by mass mass of element X 100% = % by mass mass of compound mass of compound

% by mass example  Ex. 1  The mass of carbon in a 20.0g sample of sucrose (sugar) is 8.4g. What % by mass is carbon?

% by mass example  Ex. 2  You have a 500. g sample of sucrose. Carbon in this sample has a mass of 210.5g. What percent by mass is carbon? ** Practice problems p. 76 #20-23

 What is the law of Multiple proportions?  Chemicals with different ratios of elements are different compounds.  Can compounds composed of the same element be different compounds?  Yes. If they have different mass ratios  Ex. H 2 0- water H 2 O 2 – hydrogen peroxide H 2 O 2 – hydrogen peroxide

 STOP