Embed Size (px)
Citation preview
Physical Science Chapter 15
The Classification of Matter
1
15.1 Composition of Matter
Unit Essential Question:
How does the structure of matter influence its physical and chemical behavior?
Copy this into your notebook on page 1 of chapter 15!
by what it is made of, by its physical properties, and by its chemical properties.
15. The Classification of Matter
15.1 Composition of Matter: Matter can be either a pure substance (an element or a compound) or a mixture (either heterogeneous or homogeneous.)
3
Classification of Matter
MatterSubstance
Mixture
Homogeneous
Heterogeneous
Element
Compound
HydrogenOxygenCarbon
Hydrogen oxideSodium ChlorideIron oxide
VinegarSealed soft drinksKool-aid
Solution
PizzaSaladsConcreteSoup
15:1 The Composition of Matter
A.Substances are either elements or compounds.
1. When all the atoms in a substance are alike, the substance is an element.
4
15:1 The Composition of Matter
2. A compound is a substance with two or more elements combined in a fixed
proportion.
5
15:1 The Composition of Matter
About 90 elements are found on earth.
More that 20 others have been made in laboratories, but most of these are unstable and exist only for short periods of time.
7
Elements
15:1 The Composition of Matter
Two or more substances that can be easily separated by physical means form a mixture.
A heterogeneous mixture is a mixture of different and easily distinguishable materials. Examples are salads, pizza.
7
15:1 The Composition of Matter
15
A homogeneous mixture contains two or more gaseous, liquid, or solid substances blended evenly. It is also called a solution.
15:1 The Composition of Matter
17
• Milk is an example of a specific kind of mixture called a colloid.
Colloids
4. A colloid is a type of heterogeneous mixture with particles that are larger than those in solutions but not heavy enough to settle out.
15:1 The Composition of Matter
18
• One way to distinguish a colloid from a solution is by its appearance.
Detecting Colloids
• Fog appears white because its particles are large enough to scatter light.
• Sometimes it is not so obvious that a liquid is a colloid.
• You can tell for certain if a liquid is a colloid by passing a beam of light through it.
• A light beam is invisible as it passes through a solution, but can be seen readily as it passes through a colloid. This occurs because the particles in the colloid are large enough to scatter light, but those in the solution are not. A solution does not scatter light.
Detecting Colloids
• The scattering of light by colloidal particles is called the Tyndall effect.
Video—Colloids.46 Video 2—Colloids .45
15:1 The Composition of Matter
20 e*Video—Suspensions 1 .47 Video—Suspensions 2 1.44
• Some mixtures are neither solutions nor colloids. One example is muddy pond water.
4. Suspensions—a heterogeneous mixture containing a liquid in which visible particles settle.
• Pond water is a suspension, which is a heterogeneous mixture containing a liquid in which visible particles settle.
15.2 Properties of Matter
The Big Idea: A physical property can be observed without changing the identity of the material. A chemical property describes whether it can undergo a chemical change.
27
15.2 Properties of Matter
A. Physical Property—characteristic of a material which can be observed without changing the identity of the substance in material.
• Examples of physical properties are color, shape, size, density, melting point, and boiling point.
15.215.2
28
15:2 Physical Properties
31
1. Appearance –physical description of a substance
2. Behavior—how a substance acts; for example, magnetism, viscosity, ductility
3. Physical properties such as size and magnetism can be used to separate mixtures.
15:2 Physical Properties
34
B. Physical Change—change in a substance’s size, shape or state of matter.
1. Substance does not change chemically when it undergoes a physical change. (It doesn’t change its identity.)
*Video-Physical changes 6.42
15:2 Physical Properties
35
The Identity Remains the Same
• Iron is a substance that can change states if it absorbs or releases enough energy—at high temperatures, it melts.
• Color changes can accompany a physical change, too.
15:2 Physical Properties
36
The Identity Remains the Same
• For example, when iron is heated it first glows red. Then, if it is heated to a higher temperature, it turns white.
15:2 Physical Properties
37
2. Distillation is a process for separating a mixture by evaporating a liquid and condensing its vapor.
15:2 Physical Properties
38
• The process for separating substances in a mixture by evaporating a liquid and recondensing its vapor is distillation.
Distillation
• It usually is done in the laboratory using an apparatus similar to that shown.
15:2 Chemical Properties and Changes
39
*Video—Chemical Property 1.16
• The tendency of a substance to burn, or its flammability, is an example of a chemical property because burning produces new substances during a chemical change.
C. A chemical property is a characteristic of a substance that indicates whether it can change chemically.
15:2 Chemical Properties and Changes
40
D. When one substance changes to another substance, a chemical change has occurred.
• The foaming of an antacid tablet in a glass of water and the smell in the air after a thunderstorm are other signs of new substances being produced.
15:2 Chemical Properties and Changes
42
*Video-Chemical Change 6.09
1. Some chemical changes are indicated by temperature change, smell, or bubble formation.
• Tarnish is a chemical reaction between silver metal and sulfur compounds in the air which results in silver sulfide.
• It can be changed back into silver using a chemical reaction.
15:2 Chemical Properties and Changes
43
2. Other chemical changes occur very slowly such as the formation of rust.
3. Chemical changes can be used to separate substances such as metals from their ores.
15:2
44
E. Weathering of Earth’s surface involves both physical and chemical changes.
Weathering—Chemical or Physical Change?
1. Physical—big rocks split into smaller ones; streams carry rock particles from one place to another.
2. Chemical—chemical changes occur in rocks when calcium carbonate in limestone changes to calcium hydrogen carbonate due to acid rain.
15:2
45
• A similar chemical change produces caves and the icicle shaped rock formations that often are found in them.
Chemical
15:2
46
• Suppose you burn a large log until nothing is left but a small pile of ashes.
The Conservation of Mass
• At first, you might think that matter was lost during this change because the pile of ashes looks much smaller than the log did.
47
The Conservation of Mass
• In fact, the mass of the ashes is less than that of the log.
48
The Conservation of Mass
• However, suppose that you could collect all the oxygen in the air that was combined with the log during the burning and all the smoke and gases that escaped from the burning log and measure their masses, too.
• Then you would find that no mass was lost after all.
49
The Conservation of Mass
• Not only is no mass lost during burning, mass is not gained or lost during any chemical change.
F. 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 the substances that remain after the change.
15:2 Math Skills
50
Mass of reactants = mass of products
Let’s look at page 463.
Problem 6 on page 465.
17:2 Conservation of Mass
52
Write the Law of Conservation of Mass in your notebook. Highlight this someway.
The law of conservation of mass states that matter can
neither be created or destroyed.
Video—Conservation of Mass 1.4
53
Math Practice in Text
Essential Question:
How is matter be classified?
How does the structure of matter influence its physical and chemical behavior?
Matter can be classified by what it is made of, by its physical properties, and by its chemical properties.
Prepare for test coming soon!
Remember, Homework is Due!
