SCIENCE STUDENT BOOK. 6th Grade Unit 5

Transcription

1 SCIENCE STUDENT BOOK 6th Grade Unit 5

2 Unit 5 Chemical Structure SCIENCE 605 Chemical Structure INTRODUCTION 3 1. CHEMICAL STRUCTURE 5 MASS, WEIGHT, AND STATES OF MATTER 6 EXPERIMENT 605.A (STATES OF MATTER) 8 CHEMICAL ELEMENTS AND ATOMS 10 MOLECULES AND COMPOUNDS 13 EXPERIMENT 605.B (COPPER IODIDE) 14 EXPERIMENT 605.C (CALCIUM CARBONATE) 16 SELF TEST PERIODIC TABLE 21 CHEMICAL SYMBOLS 22 ATOMIC WEIGHTS 23 ARRANGEMENT OF THE PERIODIC TABLE 27 SELF TEST CHEMICAL CHANGE 32 DIAGRAMS OF ATOMS 34 ACIDS AND BASES 40 EXPERIMENT 605.D (TESTING FOR BASES) 41 SELF TEST 3 45 LIFEPAC Test is located in the center of the booklet. Please remove before starting the unit. Section 1 1

3 Chemical Structure Unit 5 Author: Barry G. Burrus, B.S., M.A., M.Div. Editors: Alpha Omega Staff Illustrations: Brian Ring/Alpha Omega Staff MEDIA CREDITS: Pages 7: Stockbyte, belchonock, Oliver Hoffmann, istock, Thinkstock; 40: Anton Snariko, istock, Thinkstock. 804 N. 2nd Ave. E. Rock Rapids, IA MMI by Alpha Omega Publications, Inc. All rights reserved. LIFEPAC is a registered trademark of Alpha Omega Publications, Inc. All trademarks and/or service marks referenced in this material are the property of their respective owners. Alpha Omega Publications, Inc. makes no claim of ownership to any trademarks and/ or service marks other than their own and their affiliates, and makes no claim of affiliation to any companies whose trademarks may be listed in this material, other than their own. 2 Section 1

4 Unit 5 Chemical Structure Chemical Structure Introduction God has created all things that we see in our universe. The substance of all things in our universe is called matter. All matter consists of many different kinds of substances called chemicals. Chemicals make all the substances that you see around you every day. In fact, your body is made up of many different kinds of chemicals. In this LIFEPAC you will learn about the structure of chemicals. All matter contains tiny particles that make its basic structure. This structure of matter forms the basic building blocks of all chemicals. God has designed matter and chemicals with marvelous order. Human beings have discovered much about the orderly structure of matter. You will learn about some ways that people have arranged these chemicals in charts and tables. One of these, the Periodic Table, is very helpful in understanding the structure and properties of chemicals. Finally, chemicals change by combining with other chemicals. They also change from solid state to liquid to gas. You will learn more about chemical changes in this LIFEPAC. Objectives Read these objectives. The objectives tell what you should be able to do when you have completed this LIFEPAC. When you have finished this LIFEPAC, you should be able to: 1. Define and give examples of matter and chemicals. 2. Describe and give examples of the different states of matter. 3. Define and describe atoms, molecules, elements, and compounds. 4. Identify the symbols of some common elements. 5. Name some chemical elements from the Periodic Table. 6. Identify and explain the atomic number, atomic weight, and symbols of chemicals. 7. Categorize certain elements such as metals, nonmetals, radioactive substances, and rare earth elements. 8. Write the chemical formulas for some compounds. 9. Identify acids and bases. Section 1 3

5 Chemical Structure Unit 5 Survey the LIFEPAC. Ask yourself some questions about this study and write your questions here. 4 Section 1

6 Unit 5 Chemical Structure 1. CHEMICAL STRUCTURE In the beginning, God created everything that exists (Genesis 1). Everything in our physical universe is called matter. Matter is made of a great variety of substances called chemicals. The scientific study of substances and chemicals is called chemistry, and the scientists who study chemicals are called chemists. Chemistry is a very interesting subject. It permits us to see God s wonderful design of the basic structure of matter in all things that exist. All matter in the universe occupies space. It also has an amount. The amount of matter in a thing is called its mass. Therefore, matter can be defined as anything that occupies space and has mass. Much of the matter around you can be seen. For example, your clothes, your books, and your desk are all types of matter that you can see. Some matter cannot be seen. You cannot see the air around you, but it is there. Air is matter. It has mass and occupies space. However, air is matter that is in the gaseous state. In this section of the LIFEPAC, you will learn more about matter in its three basic forms or states: solid, liquid, and gas. The substances that build matter are called chemicals. All chemicals consist of tiny, basic building blocks. They are the basic stuff of all chemicals and matter. In this section of the LIFEPAC, you will learn more about these tiny units of matter and their basic structure. This will help you understand the basic structure of the chemicals that God has created. Section Objectives Review these objectives. When you have completed this section, you should be able to: 1. Define and give examples of matter and chemicals. 2. Describe and give examples of the different states of matter. 3. Define and describe atoms, molecules, elements, and compounds. Vocabulary Study these words to enhance your learning success in this section. atom (at әm). The small particle that makes up molecules. Each atom is unique for a chemical element. chemical (kem ә kәl). Any of the many substances that make up the matter of the universe. compound (kom pound). A substance whose molecules consist of atoms that are chemically united. compress (kәm pres). Squeeze together; make smaller by pressure. electron (i lek tron). An elementary particle of an atom which has a negative electrical charge. element (el ә mәnt). A pure substance that cannot be broken down into simpler substances by chemical means. gaseous (gas ē әs). In the form of gas; of or like a gas. mass (mas). The amount of matter in a body or object, usually measured in units like grams or pounds mass. matter (mat әr). Anything which has mass and occupies space. molecule (mol ә kyül). The chemical combination of two or more atoms. Section 1 5

7 Chemical Structure Unit 5 neutron (nü tron). An uncharged elemetary particle found in the nucleus of an atom. proton (prō ton). An elementary particle carrying a positive electrical charge which is located in the nucleus of an atom. swarm (swôrm). Fly or move about in great numbers. weight (wāt). The measurement of the pull of gravity on an object or body. On earth, mass and weight would be the same. Note: All vocabulary words in this LIFEPAC appear in boldface print the first time they are used. If you are not sure of the meaning when you are reading, study the definitions given. Pronunciation Key: hat, āge, cãre, fär; let, ēqual, tėrm; it, īce; hot, ōpen, ôrder; oil; out; cup, pu t, rüle; child; long; thin; /ŦH/ for then; /zh/ for measure; /u/ or /ә/ represents /a/ in about, /e/ in taken, /i/ in pencil, /o/ in lemon, and /u/ in circus. MASS, WEIGHT, AND STATES OF MATTER As a useful background to exploring chemical structure, it is helpful to examine the relationship between the mass of an object and its weight. In addition, it is also helpful to explore the three basic states of matter in which we find all chemicals: solid, liquid, and gas. Mass and weight. One of the general properties of all matter and chemicals is mass, the amount of matter contained in an object. Mass should not be confused with an object s weight. The weight of an object of a given mass is directly related to the gravitational pull on the object. Therefore, an object s weight can change depending upon the pull of gravity on the object. Since the force of gravity decreases as one moves away from earth, the weight of the object would also decrease as one moves away from earth. For example, a person with a mass of 75 pounds (mass) would weigh 75 pounds (force) on earth; however, that person would weigh very little in outer space. That same person would weigh about 12 pounds (force) on the moon because the force of gravity on the moon is about 1/6 that on earth. However, the person would still have the same mass 75 pounds (mass) whether on the earth, in outer space, or on the moon. The variations of gravitational pull of objects on earth change very little as the objects change altitude on earth. Therefore, for all practical Weight varies with gravity, but mass remains the same 6 Section 1

8 Unit 5 Chemical Structure purposes, the measurement of an object s weight on earth is the same as its mass. States of matter. Matter in the universe is normally found in three different forms or states: solid, liquid, and gas. These three states are easy to identify. Water is a common example of matter in three different states. Solid water is the ice found in your freezer and other cold places. Liquid water is the normal state of water on earth and is the form that you drink from a glass. Water, as a gas, is found as steam that is heated on your stove. In addition, water vapor (gas) is found in the atmosphere from the evaporation of earth s oceans, lakes, and rivers. Let s briefly examine a little more about solids, liquids, and gases. A solid has a specific shape and a fixed volume. For example, a block of wood has a fixed volume. A solid block of wood occupies a specific volume and has a definite shape. If you move the block of wood to another location, or if you place it in a different container, the block of wood would still have the same shape and occupy the same volume of space. If you squeezed the block of wood, it would still keep the same shape and volume. A liquid has no fixed shape. It takes the shape of its container. However, a liquid does have a fixed volume. If you have a pint of water in a glass, its volume is one pint and its shape is the same as the glass it fills. If you pour this water into a bowl, its volume will still be one pint. Steam (water vapor) is a gas However, its shape will change to the shape of the bowl that it is in. If a liquid is squeezed, the volume will not normally change. If the volume of a liquid does change under very high pressure, the change will be by such a tiny amount that the volume can be considered the same. A gas has no fixed shape of its own. It takes the shape of its container. Also, a gas does not have a fixed volume. A gas will expand if it enters a larger container, or it can be compressed or squeezed into a smaller container by increasing pressure. Ice is a solid Water is a liquid Section 1 7

9 Chemical Structure Unit 5 Try this experiment to learn about states of matter. View 605 States of Matter, from the Grade 6 SCIENCE EXPERIMENTS Video Overview. You will examine some common items about you in a home or classroom to determine properties of a solid, a liquid, and a gas. These supplies are needed: a balloon a small block of wood (or a rock) a clean, square, plastic refrigerator dish a soda pop (save it to drink) Follow these directions. Place a check mark in the box as you complete each step, and answer the questions as they are presented. 1. Identify some of the things in your room. Try to find a solid, a liquid, and a gas. Write their names in the spaces below. 1.1 a. Solid: b. Liquid: c. Gas: 2. Blow up a balloon. Squeeze it gently. 1.2 Is the statement true that a gas changes to take the shape of its container? 3. Examine the soda pop container before opening it. 1.3 Does the liquid take on the round shape of the bottle or can? 4. Open the soda pop. Pour the liquid into the square refrigerator dish. 1.4 Does the liquid take on the shape of the container? 5. Observe the bubbles of fizz which come to the top of the liquid soda pop. This fizz is due to the carbon dioxide gas which is dissolved into the drink. This is why it is called a carbonated drink. Note carefully that the bubbles of the carbon dioxide gas leave the soda pop. 1.5 Does the carbon dioxide gas have a definite shape and volume, or does it take on the shape and volume of the container? 6. Examine the piece of wood. 1.6 Does the wood have a fixed shape and volume? Experiment 605.A States of Matter 8 Section 1

10 Unit 5 Chemical Structure Write the correct letter and answer in each blank. 1.7 _ Air is matter that is in the state. a. gaseous b. convertible c. solid 1.8 _ All matter consists of many different kinds of substances called. a. photons b. chemicals c. neurons 1.9 _ Matter is material that takes up space and has. a. weight b. volume c. mass 1.10 _Your weight on the moon would be it is on the earth. a. greater than b. less than c. the same as 1.11 _Your mass on the moon would be it is on the earth. a. greater than b. less than c. the same as 1.12 _A liquid. a. has a fixed volume but takes the shape of its container b. has the volume and shape of its container c. has a fixed volume and shape _A gas. a. has a fixed volume but takes the shape of its container b. has the volume and shape of its container c. has a fixed volume and shape _A solid. a. has a fixed volume but takes the shape of its container b. has the volume and shape of its container c. has a fixed volume and shape. TEACHER CHECK initials date Section 1 9

11 Chemical Structure Unit 5 CHEMICAL ELEMENTS AND ATOMS All matter and chemicals are composed of the most basic substances called elements. There are ninety-two elements that occur naturally on earth. An additional twenty-six elements have been identified and believed to exist. Twenty-three of these were produced in labs and in nuclear reactions due to the efforts of scientists. The other three exist only in theory and don t even have names yet. When those three are proven to exist and receive names, there will be 118. You will learn more about the names and classifications of elements in Section Two of this LIFEPAC. Elements and atoms. Robert Boyle ( ) was an Irish scientist who lived most of his life in England. He is considered to be the founder of modern chemistry. Boyle introduced many new methods for determining the identity and chemical composition of substances. He also disproved a long-held theory that air, earth, fire, and water were the basic parts of all matter. Rather, Boyle suggested the idea of many elements that compose matter. Boyle defined the word element as a pure substance that cannot be broken down by chemical means. For example, copper, gold, hydrogen, carbon, and oxygen are examples of well-known elements. These elements cannot be broken down into simpler substances by chemical means. Boyle also suggested that all basic physical properties of matter and the elements were due to very tiny particles which were in motion. These tiny particles of elements are known as atoms. Atoms are the smallest part of an element that can exist as that element. Pure elements are made up of atoms of that element. For example, copper is made of copper atoms, gold is made of gold atoms, and carbon is made of carbon atoms. The atoms of each element are unique to that element. Atoms are the basic building blocks of all matter. Atoms are very, very tiny. They are more than a million times smaller than the thickness of a human hair! Atoms are so small that they cannot be seen, even with the most powerful microscopes. However, the presence of atoms can be verified by x-rays and by chemical reactions. Parts of an atom. Even though atoms are so tiny, they consists of even smaller particles! These tiny particles that make up atoms are called subatomic particles. There are three basic types of subatomic particles: protons, neutrons, and electrons. Each atom of each chemical element has a definite and unique number of these subatomic particles. Located at the center of each atom is the nucleus. The protons and neutrons are located in the nucleus. The rest of the atom outside the nucleus is Earth Electron Sun Nucleus Gravitational Attraction The planetary model of an atom Gravitational Attraction 10 Section 1

12 Unit 5 Chemical Structure mostly empty space. The electrons travel about through this empty space at incredible speeds! The electrons complete billions of trips around the nucleus in a millionth of a second! Models of atoms. A model is something that attempts to show or explain how something looks or acts. Several models have been proposed that attempt to show or explain how the subatomic particles of an atom operate. One of the first models of an atom that was developed is called the planetary model. It is also called the Bohr model, named after Niels Bohr ( ), a Danish scientist who developed a theory about the structure of an atom. The planetary model (or Bohr model) is based on the appearance of our sun with the planets of our solar system in orbit around the sun. In this case, the nucleus of the atom would correspond with the sun and the electrons would correspond with the planets that orbit the sun. However, this model is not completely accurate. Unlike the planets orbiting around the sun, the electrons in an atom do not follow regular, orderly paths. In addition, the protons and neutrons in the nucleus constantly move around at random. However, this model is still used today because it is simple and easy to draw. Another model of the atom is called the electron cloud model. This model shows better the probability that an electron is at a given point at a given time. It shows that the electrons actually swarm about the nucleus in an incredibly fast way. However, the electron cloud model is very hard to draw! Still another model of the atom can be called the simplified model. It attempts to simplify the positions of the electrons. This model helps to show how the electrons move around the nucleus, and it is much easier to draw than the electron cloud model. Perhaps none of these models are really correct, but they do attempt to show and explain how the electrons move about the nucleus of an atom. The electron cloud model The simplified model Section 1 11

13 Chemical Structure Unit 5 Match the following items elements 1.16 naturally occurring elements 1.17 founder of modern chemistry 1.18 atoms 1.19 protons, neutrons 1.20 electrons a. Robert Boyle b. Niels Bohr c. tiny parts of elements d. most basic pure substances e. twenty six f. ninety two g. subatomic particles that swarm about the nucleus h. subatomic particles of the nucleus Do the following activities _List three different models of the atom and briefly describe what each attempts to show. a. _b. c _In the space below, draw an example of an atom with one electron using the planetary model (Bohr model). Label the parts of the drawing. 12 Section 1

14 Unit 5 Chemical Structure MOLECULES AND COMPOUNDS Atoms of pure elements rarely exist alone in nature. Atoms are usually combined with other atoms to form molecules. Molecules may be defined as the chemical combination of two or more atoms. If the atoms combined in a molecule are different from each other, the material is called a chemical compound. For example, a water molecule consists of two hydrogen atoms and one oxygen atom. Since the water molecule has two different types of atoms, it is also a compound. Molecules. Molecules may consist of two or more atoms combined together. Some molecules contain thousands of atoms. In this LIFEPAC, you will study molecules which are rather simple and contain only a few atoms. The human body contains substances whose molecules are very complex. (The DNA molecule studied in the last LIFEPAC is an example.) These molecules may consist of thousands of atoms. Compounds. When atoms of one kind combine with atoms of another kind, they make compounds. As mentioned above, when two atoms of hydrogen combine with one atom of oxygen, water is formed. Both hydrogen and oxygen are normally gases at room temperature; however, they combine to form a liquid compound (water). Water is a compound whose molecules are always made of two atoms of hydrogen and one atom of oxygen. A compound may be defined as a substance whose molecules consist of different atoms which are chemically united. When you breathe the air, you inhale the element oxygen along with other gases found in the air. Oxygen in the air does not exist as single atoms. It is so reactive that two atoms of oxygen combine to form an oxygen molecule, H O H A water molecule has two hydrogen atoms and one oxygen atom written chemically as O 2. As you exhale, you breathe out carbon dioxide gas. Carbon dioxide is a compound whose molecules consists of one atom of carbon and two atoms of oxygen. It is written chemically as CO 2. The prefix dī - means two. The prefix dī - in the carbon dioxide tells us that two atoms of oxygen are combined with one atom of carbon in a carbon dioxide molecule. Another example of a common compound is table salt. Pure sodium is a metal. Pure chlorine is a gas. When sodium and chlorine are combined, they form sodium chloride, commonly called table salt. Its chemical composition is written as NaCl. This means that a molecule of salt consists of one atom of sodium and one atom of chlorine. Sodium and chlorine in their original forms as elements are very poisonous. Yet, when they are combined into salt, they are harmless. This demonstrates that a chemical compound can have properties and characteristics that are very different from the elements from which it is made. Section 1 13

15 Chemical Structure Unit 5 Try this experiment to learn about compounds. View 605 Copper Iodide, from the Grade 6 SCIENCE EXPERIMENTS Video Overview. You will combine copper and iodine to form a new compound called copper iodide. These supplies are needed: a copper penny iodine solution cotton swab a small pan for heating the penny a hot plate or Bunsen burner for heating the penny Follow these directions. Place a check mark in the box when you complete each step. 1. Ask your teacher or adult leader to approve the method of heating the penny. TEACHER CHECK initials date 2. Place the penny in the pan. Put a drop or two of iodine on top of the penny, and swab the iodine over the surface of the penny with the cotton swab. 3. Heat the pan gently until the penny gets hot and a white substance begins forming on top of the penny. 4. Note the white, dusty substance on top of the penny. It is a new compound called copper iodide. You have chemically combined copper and iodine to make copper iodide. Experiment 605.B Copper Iodide 14 Section 1

16 Unit 5 Chemical Structure Complete the following statements _The smallest part of an element is called a(n) _Everything in the physical universe is composed of which has mass and occupies space _Atoms are usually combined with other atoms to form _If the atoms combined in a molecule are different from each other, the material is called a chemical _Water is a compound whose molecules are always made of two atoms of hydrogen and one atom of is a compound whose molecules consist of one atom of carbon and two atoms of oxygen _When sodium and chlorine are combined, they form sodium chloride, commonly called _Copper and iodine combine to form a compound called. Complete the following chart _List the three normal states of matter in the following chart. Write yes or no in the space for volume and shape. STATE OF MATTER IS THE VOLUME FIXED? IS THE SHAPE FIXED? TEACHER CHECK initials date Section 1 15

17 Chemical Structure Unit 5 Try this experiment to learn more about compounds. View 605 Calcium Carbonate, from the Grade 6 SCIENCE EXPERIMENTS Video Overview. You will combine carbon dioxide (which is exhaled as you breathe) with limewater (calcium hydroxide) to form a new compound called calcium carbonate. These supplies are needed: clear limewater (See Teacher s Guide for instructions) a clear glass soda straw Follow these directions. Place a check mark in the box as you complete each step. 1. Pour at least 3 tablespoons of clear limewater into the glass. 2. Place straw into limewater. If needed, tilt the glass so that adequate limewater covers the bottom of the straw. 3. Blow gently into the straw so that your breath bubbles through the clear limewater. Continue to blow through the straw until the limewater turns noticeably cloudy or milky. 4. Observe the white, cloudy material that has formed in the limewater. This new compound is called calcium carbonate. You have formed it by combining the carbon dioxide in your breath with the calcium hydroxide in the limewater. Experiment 605.C Calcium Carbonate 16 Section 1

18 Unit 5 Chemical Structure Complete the following activities _Define atom 1.33 _Define molecule 1.34 _Define element 1.35 _Define compound 1.36 _What is formed when you blow carbon dioxide from your breath into a limewater solution containing calcium hydroxide? 1.37 _Write yes or no to the following items. Is calcium carbonate a(n): a. atom? b. molecule? c. element? d. compound? TEACHER CHECK initials date Review the material in this section in preparation for the Self Test. The Self Test will check your mastery of this particular section. The items missed on this Self Test will indicate specific areas where restudy is needed for mastery. Section 1 17

19 Chemical Structure Unit 5 SELF TEST 1 Answer true or false (each answer, 2 points) All matter in the Universe consists of many substances called elements A chemical is always the same thing as an element Chemicals can change by combining with other chemicals Scientists who study the science of substances are called geologists Air is not matter because you cannot see it On earth, the mass of an object is almost exactly the same as its weight A solid has a specific shape and a fixed weight The tiny particles of elements are called atoms A molecule may contain two atoms of the same element Electrons are located in the nucleus of an atom. Match the following items (each answer, 3 points) H 2 O NaCl CO compound elements atoms naturally occurring elements simplified model gas weight a. most basic pure substances b. ninety-two c. carbon dioxide d. salt e. water f. copper oxide g. measures gravitational pull h. combined atoms are different i. tiny particles of elements j. shows structure of atoms k. no fixed shape or volume l. the amount of matter 18 Section 1

20 Unit 5 Chemical Structure Write the correct letter and answer in each blank space (each answer, 2 points) _ Matter is material that takes up space and has. a. weight b. volume c. mass 1.022_ The mass on the moon would be it is on the earth. a. greater than b. less than c. the same as 1.023_ A liquid. a. has a fixed volume but takes the shape of its container b. has the volume and shape of its container c. has a fixed volume and shape 1.024_ A gas. a. has a fixed volume but takes the shape of its container b. has the volume and shape of its container c. has a fixed volume and shape 1.025_ A solid. a. has a fixed volume but takes the shape of its container b. has the volume and shape of its container c. has a fixed volume and shape The scientist who said matter was made of many elements and is considered the founder of modern chemistry was. a. Niels Bohr b. Francis Bacon c. Robert Boyle 1.027_ The tiny particles that make up atoms are called. a. compounds b. subatomic particles c. enzymes 1.028_ The total number of elements that have been identified is. a. 92 b. 118 c _ When carbon dioxide is bubbled through limewater, is formed. a. carbon lime b. sodium chloride c. calcium carbonate Atoms are more than times smaller than the thickness of human hair. a. a million b. ten thousand c. a thousand Section 1 19

21 Chemical Structure Unit 5 Create drawings with labels of electron(s) and nucleus (each drawing, 5 points) _ In the space below, draw an example of an atom using the planetary model _ In the space below, draw an example of an atom using the simplified model. Write yes or no on each blank line (each answer, 2 points) _ Is copper oxide a(n): a. atom? b. molecule? c. subatomic particle? d. element? e. compound? Answer the following questions (each answer, 5 points) _ What is the electron cloud model and what does it attempt to show? _ What is the definition of an element? SCORE TEACHER initials date 20 Section 1

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