understand the teks - mastery education · scientists use chemical and physical properties to...

Understand the TEKS

It is important that you are able to recognize the difference between a physical property and a chemical property of a substance.

A physical property is a characteristic of a substance that can be observed at any time.

A chemical change occurs when a substance changes into a different substance.

A chemical property is a characteristic of a substance that can be seen during a chemical change.

Guided Instruction

Read the following information and answer the questions.You can recognize other people by their faces, heights, and hair.

You can recognize substances in the same way. Instead of faces and hair, substances have physical and chemical properties.

Physical properties are easy to observe by using your senses of sight, touch, hearing, smell, and taste. (Of course, some things are not safe to touch or smell or taste!) Some physical properties of a banana are the yellow color of its skin and its long, skinny shape.

Another example of a physical property is solubility, or the ability to dissolve in liquid. Melting point, boiling point, and freezing point are also physical properties.

Physical properties and physical changes are closely linked. Physical changes affect the physical properties of an object without changing the object’s makeup. If you cut a banana into small pieces, it no longer has a long, skinny shape. However, it is still a banana, so cutting it up was a physical change.

Melting, boiling, and freezing are also physical changes. Substances do not change into new substances when they melt, boil, or freeze. Unlike physical changes, a chemical change actually changes the makeup of a substance—when water undergoes a chemical change by reacting with another substance, the product of the change is not water anymore.

A chemical property is a property that can only be observed during a chemical change. For example, one of copper’s chemical properties is that it gradually forms a patina, or a greenish coating, on its surface. When copper forms a patina, it is actually changing into a different substance. Another example of a chemical property is flammability, or the ability to burn. When wood burns, it changes into a combination of ash and smoke.

Often, if a substance changes color, it likely has undergone a chemical change. One way to tell rusting is a chemical change is that rust is a different color than iron. The formation of gas bubbles or a solid precipitate as well as temperature changes are also signs of a chemical change.

Scientists use chemical and physical properties to classify and organize substances. For example, elements are classified as metals, nonmetals, and metalloids. Each of these classes has different physical properties. Metals conduct electricity well, have a shiny luster, and are malleable. Malleable means that they can be pounded out into a shape without breaking. Nonmetals tend to have a dull luster, do not conduct electricity, and are not malleable. They break into pieces when you pound them. Metalloids have properties in between metals and nonmetals. For example, a metalloid may be shiny but does not conduct electricity well.

Words to Knowphysical propertychemical changechemical property

TEKS 6.6(A) Compare metals, nonmetals, and metalloids using physical properties such as luster, conductivity, or malleability.

How Do I Distinguish between Physical and Chemical Properties?Lesson15

Science • Level F Copying is illegal. Measuring Up to the Texas Essential Knowledge and Skills108

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SAMPLE

1. Name two physical properties of a banana.

2. List two other physical properties of a banana.

3. What is a chemical property?

4. What type of element is shiny and a good conductor of electricity?

Critical Thinking

Answer the following questions.

1. When can chemical properties be observed?

2. What type of property is shininess?

3. Name one physical property and one chemical property of an iron nail.

MasteryEducation.com Copying is illegal. Unit 4 • How Can I Identify and Change Types of Matter? 109

How Do I Distinguish between Physical and Chemical Properties? Lesson 15


SAMPLE

Read the paragraph and answer the questions.Iron is a hard, grayish solid at room temperature. Iron has a density of 7.9 g/cm3 and melts at 1,535°C.

You can flatten a piece of iron by hitting it with a hammer. If you leave a piece of iron outside in moist air, a reddish coating called rust forms on its surface. Rust crumbles easily and sometimes falls off the iron, leaving the surface of the iron pitted.

4. List three physical properties of iron.

5. Explain which part of the paragraph describes a chemical change.

6. What are the conditions necessary for a chemical change in iron to form rust?

7. What are some differences between rust and iron?


Lesson 15 How Do I Distinguish between Physical and Chemical Properties?


SAMPLE

★ Practice

DIRECTIONS Read each question. Then circle the letter for the correct answer.

1 Which of the following is a chemical property of charcoal?

A It is black.

B It is flammable.

C It can float.

D It can break.

2 You use a magnet to get iron filings out of a pile of sand.

What did you do?

F You used a difference in density.

G You used a chemical change.

H You used a physical property.

J You used a chemical property.

3 What is a property of metals?

A Conducts electricity

B Breaks easily

C Dull luster

D Powdery texture

4 A piece of wood burned and ashes remain. How do you know a chemical change took place?

F Wood has the same physical properties as the ashes.

G You can mix air and ashes and get the wood back.

H The wood changed into a different type of substance.

J The chemical property of wood and ashes are the same.

5 A copper statue turns green, is dented by a rock, becomes warm in the sun, and becomes cool at night. What is a sign that a chemical change has happened to the statue?

A It changes color.

B It changes shape.

C It becomes warm.

D It becomes cool.

2

4

5

MasteryEducation.com Copying is illegal. Unit 4 • How Can I Identify and Change Types of Matter? 111

How Do I Distinguish between Physical and Chemical Properties? Lesson 15


SAMPLE

1 Terrence is conducting an experiment and needs an object that can conduct electricity. Which of the following is a good fit for Terrence’s experiment?

A Metalloids

B Metals

C Nonmetals

D All of the above are a good fit for the experiment.

2 Which of the following statements best supports why a chemical change has occurred when burning sugar?

F A chemical change always involves the use of heat.

G The burnt sugar cannot return to its original state.

H The burning of the sugar released a distinct odor.

J No chemical change has occurred because the sugar is still sugar.

3 What are some physical properties of gas?

A Pressure, volume, and flammability

B Pressure, volume, and bitter taste

C Pressure, volume, and temperature

D Gas does not have any physical properties

4 Which of the following is a chemical property?

F Melting point

G Boiling point

H Solubility

J Acidity

5 Which of the following is a property of nonmetals?

A Ductile

B Malleable

C Nonconductive

D Shiny

6 Samantha is conducting an experiment on a mystery substance. She observes that the substance is white, rough, odorless, and bubbles when placed in vinegar. Which of the following is a chemical property of the substance?

F Color

G Texture

H Odor

J Reactivity with acid

2

★ Assessment

DIRECTIONS Read each question. Then circle the letter for the correct answer.


Lesson 15 How Do I Distinguish between Physical and Chemical Properties?


SAMPLE

understand the teks - mastery education · scientists use chemical and physical properties to...

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