8/6/2019 Unit2 Objective 1 & 2 Teacher Notes

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  Name _______________________________________ Period _________________________ 

Unit 2: Matter 

Objective 1: Distinguish among mixtures and pure substancesObjective 2: Differentiate between physical and chemical properties and changes.

NOTES:

Pure Substance: Something made up of only 1 kind of moleculey  R emember, a molecule can either be a compound or an element

y  Examples:

o  Water (H2O) - compoundo  Salt (NaCl) - compound

o  Sand (SiO2) - compound

o  Silver (Ag) - element

o  Oxygen (O2) - elemento  Ethanol (C2H6) - compound

y  You can have several molecules together. As long as they are the same, it is a puresubstance

y  Molecular models:

Mixture: When two or more pure substances combine, but they don¶t chemically bond

y  The different types of molecules stay separated

y  Each part keeps its own properties

y  They can be physically separated

o  Filtration, evaporation, distillation, magnetism

y  Molecular models:

2 different elements: 2 different compounds: A compound and an element:

Heterogeneous mixture: A mixture in which the parts are very different

y  Can see the different parts

o  Examples:

Chex mix, salad, sand and water, oil and water 

y  Also includes liquids that you cannot see througho  Examples:

Milk, mud, ranch salad dressing

o  Includes suspensions and colloids

Homogeneous mixtures: A mixture in which the parts are similar and well blended

y  Cannot see the different partso  Examples:

Air, Alloys (metal mixtures like steel)

y  Solutions: homogenous mixtures when things dissolve

o  You can see through them

o  You can shine a light straight through them

o  Examples:Salt water, sugar water, alcohol and water 

8/6/2019 Unit2 Objective 1 & 2 Teacher Notes

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  Name _______________________________________ Period _________________________ All substances have properties, or characteristics.

Physical property: a characteristic that

y  Can be observed with the senses

y  Can be determined without DESTR OYI NG/ Chemically changing the object

y  Examples:o  Color 

o  Shapeo  Odor 

o   Density

o   M elting/boiling point 

o   Malleability

o   Lu ster 

Chemical property:

y  Indicates how a substance reacts with something elsey  The substance is DESTR OYED/ chemically changed when observing it

y  Examples:o  Combustibility

o  Flammability

o  Ability to rust

o  R eacts with a base to form water 

Physical Change: a change in ONLY the appearance of something

y  Examples:o  Smashing, crushing, crinkling, tearing

o  Dissolving

o  Change of state (solid/liquid/gas)

Chemical Reaction/Change: a pure substance changes into an entirely different pure substance

y  Look for words like:o  R ust

o  Decompose

o  Burn/ combust

o  Synthesize

y  Evidence:o  Color change

o  Precipitate (2 liquids form a solid)

o  Gas production (not from boiling)

o  Temperature change (not from heating or cooling

8/6/2019 Unit2 Objective 1 & 2 Teacher Notes

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GR OUPWORK :

Check the correct box:

Physical or Chemical Properties: Physical changes or Chemicalreactions

Physical Chemical Physical Chemical

color Condensation of water 

 combustibility R usting iron

hardness Cutting wood

density Ice melting

mass Milk going sour 

amount of energy Mg in HCl forms a gas

 melting point Vapor forms from boiling

volume Condensation of water  

odor  Two liquids make a solid

tendency to corrode Banana rotting

First, decide if it is a pure substance or a mixture.If it is a mixture: check heterogeneous or homogeneous

If it is a pure substance: check compound or elementMixture Pure Substance

Heterogeneous Homogeneous Compound Element

Aluminum

Salad dressing

K ool aid

Sugar 

Air 

 Nitrogen

14 carrot jewelry

soil

Chalk (CaCO3)

Bronze

yogurt

Salt

Sodium

8/6/2019 Unit2 Objective 1 & 2 Teacher Notes

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INDEPENDENT PRACTICE

Chemical and Physical Properties- 

Define

Chemical Property-

Physical Property-

Color Weight Density

Flammability Reactivity Ability to Rust 

Chemical and Physical Changes-

List three ways you know a chemical reaction has occurred-

Are the following chemical or physical changes?

Baking Soda and Vinegar Boiling

Freezing Leaves changing color

Frying an Egg Burning Wood

Breaking a pencil Rusting Car

How do you know if these are chemical or physical changes?

Elements, Compounds and Mixtures- 

DefineElement-

Compound-

Homogeneous Mixture-

Heterogeneous Mixture-

Elements or Compounds?

H2O N2 CH4

O2 Al H2SO4 

Homogeneous or Heterogeneous?Pile of Rocks Lemonade

Iced Tea Pennies and Dimes

Oil and Water Sea Water

Why are elements and compounds considered pure substances?

8/6/2019 Unit2 Objective 1 & 2 Teacher Notes

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  Name _______________________________________ Period _________________________