1. Unit 4: The Nature of Matter
Table of Contents 15
Unit 4: The Nature of Matter
Chapter 15: Classification of Matter
15.1: Composition of Matter
15.2: Properties of Matter

2. Substances
A substance is a type of matter with fixed, constant composition
May be an element or a compound
You can write a formula for any substance
Examples:

3. Composition of Matter
15.1
Elements
element –
Pure Substance- all the atoms in a have the same identity
Atoms are the building blocks of elements
Examples: ?

4. Elements 15.1 About 90 elements are found on Earth.
Composition of Matter
15.1
Elements
About 90 elements are found on Earth.
More than 20 others have been made in laboratories, but most of these are unstable and exist only for short periods of time.

5. Important elements
Lead (Pb) has high density, blocks radiation, used in dentist offices in aprons
Aluminum (Al) is bendable and resists corrosion. Is strong and lightweight. Used in airplanes, cans, bikes

6. Composition of Matter
15.1
Compounds
Compound- two or more elements combine to form substances.
It has a specific chemical composition and you can write a formula for it.
Examples?

7. Compounds 15.1 Composition of Matter Sodium is a silvery metal element
chlorine is a green poisonous gas element
Chemically combined, they make table salt with formula NaCl which is a compound

8. Composition of Matter
15.1
Mixtures
A mixture- Material made up of two or more substances that can be easily separated by physical means.
Examples?

9. Heterogeneous Mixtures
Composition of Matter
15.1
Heterogeneous Mixtures
heterogeneous mixture -A mixture in which different materials can be distinguished easily by looking at it.
A microscope might be necessary
Examples?

10. Composition of Matter
15.1
Suspensions
suspension, a heterogeneous mixture containing a liquid in which visible particles settle.
Examples?
River water, salad dressing

11. Composition of Matter
15.1
Colloids
colloid –heterogeneous mixture with particles that are larger than those in solutions but not heavy enough to settle out.
Kinds of looks homogeneous but is really heterogeneous, especially under a microscope
Examples?
Paint
Whole milk
Fog
Butter
Mayonnaise

12. Composition of Matter
15.1
Detecting Colloids
Tyndall effect- scattering of light by colloidal particles. Laser light works best

13. Composition of Matter
15.1
Homogeneous Mixtures
Homogeneous mixture two or more gaseous, liquid, or solid substances blended evenly throughout.
You can only see one thing
Examples?
Ice tea – sugar, water, tea
Air – nitrogen, oxygen
Alloys – like brass – made of copper and zinc

14. Homogeneous Mixtures 15.1 Solution – defined as a homogeneous mixture
Composition of Matter
15.1
Homogeneous Mixtures
Solution –
defined as a homogeneous mixture
Particles cannot be seen with a microscope
Will never settle to the bottom of their container.
May be solid, liquid or gas
Made of solvent and solute
Substances cannot be separated by filtering

15. The table summarizes the properties of different types of mixtures.
Composition of Matter
15.1
The table summarizes the properties of different types of mixtures.

16. Concept map – classifying matter

17. Section Check
15.1
Question 1
A _______ is a type of matter with a fixed composition.
A. colloid
B. mixture
C. substance
D. solution

18. Section Check
15.1
Answer
The answer is C. A substance can be either an element or a compound.

19. Question 2 15.1 How many elements are found on Earth? A. 5 B. 10 C. 30
Section Check
15.1
Question 2
How many elements are found on Earth?
A. 5
B. 10
C. 30
D. 90

20. Section Check
15.1
Answer
The answer is D. About 90 elements are found on Earth, and more than 20 have been made in laboratories.

21. Question 3 15.1 How are compounds different from mixtures?
Section Check
15.1
Question 3
How are compounds different from mixtures?

22. Section Check
15.1
Answer
The atoms in compounds are combined in fixed proportions and cannot be separated by physical means. A mixture is made of two or more substances that can be easily separated by physical means.

23. Properties of Matter
15.2
Physical Properties
physical property - characteristic of a material that you can observe without changing the identity of the material.
Examples: color, shape, size, density, melting point, and boiling point.

24. Physical properties Appearance – like color, shape
Behavior – like viscosity, magnetism
You can use these properties to separate items in a mixture

25. Behavior 15.2 You can separate a sand/iron mixture by using a magnet
Properties of Matter
15.2
Behavior
You can separate a sand/iron mixture by using a magnet

26. The Identity Remains the Same
Properties of Matter
15.2
Physical Change
The Identity Remains the Same
physical change -A change in size, shape, or state (gas, liquid, solid) of matter.
Will still have the same formula
Examples?
Boiling, melting

27. The Identity Remains the Same
Properties of Matter
15.2
The Identity Remains the Same

28. Using Physical Change to Separate
Properties of Matter
15.2
Using Physical Change to Separate
Distillation- Separating substances in a mixture by evaporating a liquid and recondensing its vapor
Separation occurs due to different boiling points
For example, an alcohol/water mixture can be distilled because the alcohol has a lower boiling point than water.

29. Properties of Matter
15.2
Distillation

30. Chemical Properties and Changes
Properties of Matter
15.2
Chemical Properties and Changes
chemical property- any characteristic of a material that you can observe that produces new substances (element or compounds) with new properties and new formulas.
Examples?
Flammability, rusting

31. Properties of Matter
15.2
The Identity Changes
chemical change - A change from one substance to another. The identity of the substance changes
Indications of chemical change:
Bubbles
Temperature Change
Precipitate formation
Color change
Click image to view movie

32. Detecting Chemical Change
Properties of Matter
15.2
Detecting Chemical Change
If you leave a pan of chili cooking unattended on the stove for too long, your nose soon tells you that something is wrong.
This burnt odor is a clue telling you that a new substance has formed.

33. Usefulness of chemical changes
Tarnished silver (silver reacted with sulfur) can be cleaned with baking soda and aluminum in hot water. This turns the tarnish (silver sulfide) back into pure silver.

34. Weathering Physical changes – rocks splitting
Chemical changes – acid rain dissolving rocks over time

35. The Conservation of Mass
Properties of Matter
15.2
The Conservation of Mass

36. The Conservation of Mass
Properties of Matter
15.2
The Conservation of Mass
Law of conservation of mass, the mass of all substances before a reaction equal the mass of all the substances that remain after the change.
Mass of reactants = mass of products
no mass is lost during a chemical or physical reaction.

37. Example of law of conservation of mass
If 18 grams of hydrogen (H) reacts with 633 grams of chlorine (Cl), how much hydrochloric acid (HCl) will form?
Write words:
18 grams H grams Cl  651 grams HCl

38. Another example
Methane reacts with oxygen (burning) to form carbon dioxide and water. How many grams of water can be formed if 24 grams of methane reacts with 96 grams of oxygen and 66 grams of carbon dioxide forms? Solve: 24 grams methane + 96 grams oxygen  66 grams carbon dioxide + 54 grams water

39. Question 1 15.2 Which of the following is a chemical property?
Section Check
15.2
Question 1
Which of the following is a chemical property?
A. boiling point
B. density
C. flammability
D. melting point

40. Section Check
15.2
Answer
The answer is C. Flammability indicates whether a substance will undergo the chemical change of burning.

41. Section Check
15.2
Question 2
A characteristic of a material that can be observed without changing the identity of the substances that make up the material is a _______.

42. Section Check
15.2
Answer
The answer is physical property. Examples of physical properties include color, shape, and density.

43. Section Check
15.2
Question 3
What is the law of conservation of mass?

44. Section Check
15.2
Answer
According to the law of conservation of mass, the mass of all substances that are present before a chemical change equals the mass of all substances that remain after the change.

45. 15
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46. End of Chapter Summary File