1. Properties or Matter

2. 2.1 Classifying Matter
Why are elements and compounds classified as pure substances?
How do mixtures differ from pure substances?
What is the main difference among solutions, suspensions, and colloids?

3. Pure Substances = substances -matter that has exactly the same composition (fixed and uniform) -table salt and table sugar
Compound: Dry Ice
Element: Gold
Matter can be pure, such as an element (gold), or a compound (water).

4. Elements
Cannot be broken down into simpler substances by ordinary chemical changes
Only about 100 known
An atom is the smallest particle of an element that has the chemical properties of that element. (An element consists of atoms of only one type.)
At room temperature, most elements are solids.
Al - Aluminum (aluminum foil, soft drink cans)
C- Carbon (main element in pencil lead)
Some elements are gases at room temp.
Oxygen and nitrogen
Two elements are liquids at room temperature
Bromine and mercury (both extremely poisonous)
Turn to page 39 in your textbook. What are some characteristics of the elements pictured here?

5. Elements are represented by Symbols
Jons Berzelius (Swedish chemist) suggested chemists use symbols
(Class participation points opportunity!!!)
Symbols allow scientists to communicate without confusion (regardless of language)

6. A molecule is a group of atoms that are held together by covalent bonds so that they move as a single unit.

7. Compounds
A substance made from two or more simpler substances joined in a fixed proportion (A substance made up of two or more different types of atoms bonded together.)
Water (H2O)
Properties differ from those of the substances from which the compound is made
O and H are gases at room temperature, H can fuel fire, O can keep it burning
Water is a liquid at room temperature but does not burn or help other substances to burn

8. Comparing and Contrasting Molecules and Compounds

9. Coming Soon!

10. Mixtures Properties can vary Composition is not fixed
Matter can be a mixture. Mixtures are a combination of two or more substances that do not combine chemically but remain the same individual substances. Mixtures can be separated by physical means. Mixtures contain two or more pure substances.
Properties can vary
can retain some properties of their individual substances but properties are less constant than properties of a substance
Composition is not fixed
Think of a salad
Heterogeneous and Homogeneous Mixtures
Hetero – parts are noticeably different(sand=light and dark parts)
Homo – parts are difficult to distinguish(stainless steel=iron, chromium and nickel)
How can you tell sand is a heterogeneous mixture?

11. Mixtures can be solutions, suspensions and colloids
Mixtures can be solutions, suspensions and colloids. Mixtures are classified by the size of their largest particles.
Solutions – sugar water, windshield wiper fluid
–homogenous mixture
–will not separate over time
Suspensions – sandy water, Italian salad dressing
– heterogeneous mixture
– separates into layers over time
– scatters light
Colloids – fog, homogenized milk
– homogeneous or heterogeneous depending on approach
– water, sugar, proteins, fats
– do not separate into layers
*What happens to suspended particles over time?
*How does a mask prevent a worker from
inhaling particles of plastic suspended in the air
after they’ve been sanded from a surfboard ?
*Consider creating a three part Venn diagram on mixtures.

12. Delving Deeper into Mixtures
Solutions
Suspensions
Colloids
A solution is a homogeneous mixture of two or more components. The dissolving agent is the solvent. The substance which is dissolved is the solute. The components of a solution are atoms, ions, or molecules, which makes them 10-9 m or smaller in diameter.
The particles in suspensions are larger than those found in solutions. Components of a suspension can be evenly distributed by a mechanical means, like by shaking the contents, but the components will settle out.
Particles intermediate in size between those found in solutions and suspensions can be mixed such that they remain evenly distributed without settling out. These particles range in size from 10-8 to 10-6 m in size and are termed colloidal particles or colloids. The mixture they form is called a colloidal dispersion. A colloidal dispersion consists of colloids in a dispersing medium.
Example: Oil and water, Fine sand in water, Paint, Dust in air, Droplets of oil in air
Examples: Sugar dissolved in water, Salt dissolved in water Carbon dioxide or oxygen in water, Water vapor in air, Hexane in paraffin wax, Mercury in gold
Example: Aerosol (liquid dispersed in a gas - fog, mist, clouds) Foam (gas dispersed in a liquid - soda (CO2 dissolved in water), whipped cream) Solid Foam (gas dispersed in a solid - Styrofoam, plaster) Emulsion (liquid dispersed in a liquid - butter, milk)

13. Processing the Concepts

14. Matter Anything with mass and volume.
Substance Matter with constant composition
Mixture Matter with variable composition
Element Substance made up of only one type of atom
Compound Two or more elements that are chemically combined
Heterogeneous Mixture Mixtures that are made up of more than one phase
Homogeneous Mixtures Also called solutions. Mixtures that are made up of only one phase
Examples - gold, silver, carbon, oxygen and hydrogen
Examples - water, carbon dioxide, sodium bicarbonate, carbon monoxide
Examples - sand, soil, chicken soup, pizza, chocolate chip cookies.
Examples - salt water, pure air, metal alloys, seltzer water.

15. Data Analysis: Do the Contents of Two Cans of Mixed Nuts meet FDA Regulations? (p 42)
How are the two brands of mixed nuts alike? How are they different?
What is the percent by mass of each type of nut in each can?
Do the contents of each can meet the FDA regulations? Explain
On the Brand A label, the nuts are listed in this order: peanuts, Brazil nuts, almonds, cashews, pecans, and hazelnuts. What do you think determines the order?

16. 2.2 Physical Properties
When can physical properties be observed? What observations might indicate that a physical change has occurred?

17. A physical property is any characteristic of a material (substance) that can be observed or measured without changing the compositions (identities) of the substances in the material. (See pages )
Viscosity
Conductivity
Malleability
Hardness
Melting point
Boiling point
Density
Consider a Layered
Foldable Reflection

18. Using Physical Properties
To Identify Materials
To Choose Materials
To Separate Mixtures
Filtration
Distillation

19. • Physical properties can be observed without changing the substance.
• Physical changes can change some physical properties but do not change the substance.

20. Recognizing Physical Changes
Some of the properties change but substances in the material remain the same
Water Liquid Gas
Butter (solid) in a pan (heated) liquid butter
Crumpling or slicing changes size and shape but not composition
Some physical changes can be reversed and others cannot (braids and ice, verses sliced tomatoes or peeled oranges)

21. 2.3 Chemical Properties When can chemical properties be observed?
What observations might indicate that a chemical change has occurred?
What is the difference between chemical and physical changes?

22. Observing Chemical Properties
Chemical properties have the ability to produce a change in the composition of matter.
Can only be observed changing into different substances
Flammability (combustion)
Reactivity
rusting(oxidation)
tarnishing

23. Recognizing Chemical Changes
Change in color
Production of a gas
Forming a precipitate

24. Comparing and Contrasting Physical and Chemical Properties
Do you have ideas for how this information could be organized using a tool a scientist might use?
Physical or chemical change?

25. Compare and Contrast Physical or Chemical Changes
Use a Venn Diagram, Table or T – chart
One Example:
Physical Change
Chemical Change
Composition of matter remains the same
Composition of matter changes
Some can be reversed and some cannot
Can be reversed but it’s not easy

26. What Should Be Done With Arsenic-Treated Wood?
Another opportunity for class participation credit… Read Research Complete a Current Event form