Chemical Bonds. Chapter Resources. Includes: Glencoe Science. Reproducible Student Pages. Teacher Support and Planning TRANSPARENCY ACTIVITIES

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1 Glencoe Science Chapter Resources Chemical Bonds Includes: Reproducible Student Pages ASSESSMENT Chapter Tests Chapter Review HANDS-ON ACTIVITIES Lab Worksheets for each Student Edition Activity Laboratory Activities Foldables Reading and Study Skills activity sheet MEETING INDIVIDUAL NEEDS Directed Reading for Content Mastery Directed Reading for Content Mastery in Spanish Reinforcement Enrichment Note-taking Worksheets TRANSPARENCY ACTIVITIES Section Focus Transparency Activities Teaching Transparency Activity Assessment Transparency Activity Teacher Support and Planning Content Outline for Teaching Spanish Resources Teacher Guide and Answers

2 Directed Reading for Content Mastery Overview Chemical Bonds Directions: All of the statements below are false as written. In the space provided, write a term or phrase that makes the statement true when it is substituted for the underlined words. 1. The properties of a compound are the same as the properties of the elements that it contains. 2. Superscript numbers in chemical formulas tell how many atoms of each element are found in a unit of compound. 3. All the noble gases except helium have 18 electrons in their outer energy level. 4. A(n) chemical formula is the force that holds atoms together in a compound. 5. An ion is a(n) neutral particle that has either more or fewer electrons than protons. 6. Oxidation numbers are written as subscripts. 7. A(n) covalent bond is the force of attraction between the opposite charges of the ions in an ionic compound. 8. The charge on a compound is always positive. 9. Equal sharing of electrons in covalent bonds results in polar molecules. 10. Only two identical atoms can share electrons unequally. 11. A binary compound contains five different elements. 12. An oxidation number tells how many protons an atom must gain, lose, or share to become stable. 13. The oxidation number of the copper(ii) ion is When writing chemical formulas, add superscripts so that the sum of the oxidation numbers equals ten. 15. A polyatomic ion never has a positive or negative charge. 16. The polyatomic ion SO 4 2 is called the sulfide ion. Chemical Bonds 19

3 Directed Reading for Content Mastery Section 1 Stability in Bonding Section 2 Types of Bonds Directions: In the blanks, write the terms from the word list that complete the definition. Words can be used more than once. positive element(s) compound(s) energy level(s) charged number(s) force(s) atom(s) ion(s) electron(s) negative 1. A chemical formula tells what make up a and the exact of atoms of each element in a unit of compound. 2. An atom is chemically stable when its outer is completely filled with. 3. A chemical bond is a that holds together in a compound. 4. An that has lost or gained is called an ion. 5. An ionic bond is the of attraction between the opposite charges of the in an ionic. 6. The attraction that forms between when they share is known as a covalent bond. 7. A polar molecule has a slightly end and a slightly end. 8. A nonpolar molecule does not have oppositely ends. Only atoms that are exactly alike can share their equally. 20 Chemical Bonds

4 Directed Reading for Content Mastery Section 3 Writing Formulas and Naming Compounds Directions: The words in each group below are related. Using all the words in the group, write a sentence that shows how the words are related. Example: compound, properties, elements The properties of a compound differ from the properties of the elements that make up the compound. 1. hydrate, compound, water 2. oxidation number, element, electrons 3. zero,oxidation numbers, noble gases 4. oxidation number, Roman numeral, element 5. chemical formulas, neutral, compounds 6. polyatomic, covalent, charged 7. Greek prefixes, binary covalent compounds 8. charge, oxidation number, ionic compounds Chemical Bonds 21

5 Directed Reading for Content Mastery Key Terms Chemical Bonds Directions: Match each term in Column I with its description in Column II. Write the letter of the correct term in the space provided. Column I Column II 1. binary compound a. number that indicates how many electrons an atom must gain, lose, or share to 2. chemically stable become stable 3. nonpolar molecule 4. ion 5. ionic bond 6. polar molecule 7. oxidation number 8. chemical formula 9. covalent bond 10. hydrate 11. chemical bond 12. polyatomic ion b. shorthand that tells what elements a compound contains and the exact number of atoms of each element in a unit of the compound c. positively or negatively charged, covalently bonded group of atoms d. compound composed of two elements e. describes an atom that has a full outermost energy level f. molecule that has a slightly positive end and a slightly negative end g. the attraction that forms between atoms when they share electrons h. the force that holds atoms together in a compound i. a compound that has water chemically attached to it j. the force of attraction between the opposite charges of the ions in an ionic compound k. molecule made of two identical atoms that share the electrons equally l. a charged particle that has either more or fewer electrons than protons 22 Chemical Bonds

6 1 Reinforcement Stability in Bonding Directions: Each statement below contains a pair of terms or phrases in parentheses. Circle the term or phrase that makes each statement true. 1. The properties of a compound are (the same as, different from) the properties of the elements that make up the compound. 2. Na and Cl are chemical (symbols, formulas). 3. NaCl and NaOH are chemical (symbols, formulas). 4. In the formula H 2 O, the number 2 is a (subscript, superscript). 5. The number 2 in the formula H 2 O tells you that each unit of this compound contains two (hydrogen, oxygen) atoms. 6. If a symbol in a chemical formula does not have a subscript after it, a unit of that compound contains (no atoms, one atom) of that element. 7. The total number of atoms in Fe 2 O 3 is (two, five, six). 8. There are (three, seven, ten) different elements in H 2 SO An atom is chemically stable if its outer energy level (is filled with, contains no) electrons. 10. For atoms of most noble gases and most other elements, the outer energy level is full when it has (3, 8) electrons. 11. The noble gases do not readily form compounds because they (are, are not) chemically stable. 12. A chemical bond is a (force, chemical) that holds atoms together in a compound. 13. Chemical bonds form when atoms lose, gain, or (share, multiply) electrons. Directions: Complete the table below by using the formula of each compound to identify the elements that each compound contains and the number of atoms of each of these elements in a unit of the compound. The first formula has been done for you Formula Element 1 Element 2 Element 3 H 2 O 2 hydrogen 1 oxygen NaOH NaCl NH H 2 SO 4 SiO 2 Chemical Bonds 27

7 2 Reinforcement Types of Bonds Directions: Study the diagram below. Write your answers to the questions in the spaces provided. A. B. 12P 12N 8P 8N 1. If atom A loses electrons to atom B, a. how many electrons will atom A lose? b. how many electrons will atom B gain? c. what will be the oxidation number of atom A? d. what will be the oxidation number of atom B? e. what will be the total charge of the compound formed? f. what type of bond will form? 2. Explain why an element s oxidation number is related to the group on the periodic table to which it belongs. Directions: Complete the table comparing ionic compounds and covalent compounds. Characteristic Ionic compounds Covalent compounds 3. How the compound is formed 4. Smallest particle 5. Usual state at room temperature 28 Chemical Bonds

8 3 Reinforcement Writing Formulas and Naming Compounds Directions: Answer the following questions in the spaces provided. Refer to the periodic table for help. 1. Define an oxidation number. 2. What is the usual oxidation number of oxygen? Of hydrogen? 3. What is the sum of all the oxidation numbers in any compound? 4. Explain the difference between CoCl 2 6H 2 O and anhydrous cobalt chloride. Directions: Use the periodic table in your textbook to identify the oxidation numbers of the elements in each group. Group Oxidation number Directions: Write the formulas for the following compounds. Use the periodic table in your textbook for help. 10. copper(ii) sulfate 11. calcium chloride 12. iron(ii) oxide 13. copper(i) oxide 14. sodium sulfide 15. magnesium sulfate heptahydrate Directions: Complete the following table by providing the name of the compound and the total number of atoms in each formula given. Formula Name Number of Atoms 16. NH 4 OH 17. NH 4 C Ag 2 O 19. K 2 SO Ca (NO 3 ) Na 2 S Chemical Bonds 29

9 1 Enrichment Electron Dot Diagrams The electrons in an atom s outer energy level are the electrons that are important to consider in chemical bonds and chemical reactions. These electrons can be represented in a diagram called an electron dot diagram. The outermost electrons are drawn as dots around the chemical symbol. In this activity, you will draw electron dot diagrams for several elements. Procedure 1. Write the symbol for the element. For electron dot diagrams, this symbol represents the nucleus and all of the electrons of the atom except the outermost electrons. Example: The symbol for chlorine is Cl. In an electron dot diagram, this symbol represents the nucleus and the ten electrons in the first two energy levels. 2. Use the periodic table to determine how many outer electrons the element has. Do this by finding to which group the element belongs. Example: Chlorine belongs to Group 17, the halogens, which have seven outer electrons. Conclude and Apply 1. Write electron dot diagrams for the elements listed. a. hydrogen e. aluminum b. neon f. fluorine c. sodium g. argon d. calcium h. potassium 3. Draw a dot to represent each electron in the outer level of the element. Two electrons can be placed on each side of the symbol. The first two electrons should be paired on the right side of the symbol. The rest of the outer electrons should be distributed counterclockwise one by one around the other sides of the symbol. Example: The electron dot diagram for chlorine is 2. Why do sodium and potassium have the same number of dots in their electron dot diagrams? What does this tell you about the chemistry of these two elements? Cl 30 Chemical Bonds

10 2 Enrichment Paper Chromatography Paper chromatography uses polarity to separate substances from a solution. The polarity of a substance affects how fast a particular substance dissolved in a particular solvent can move along paper. Because the rates of movement are very specific, chromatography can also be used to identify substances. In paper chromatography, a small sample of a solution is placed on absorbent paper. A solvent passes through the sample and carries the dissolved substances. The various substances in the solution move outward at different rates. The procedure described below demonstrates how components of a mixture can be separated. If a procedure is set up in a way that can identify how far the solvent travels and how far the dissolved substance travels, these distances can be measured and compared. The number obtained by dividing the distance the dissolved substance traveled by the distance the solvent traveled is known as R f.ifspecifics of the procedure such as temperature, solvent, and type of paper are controlled, the R f values can be used to identify the substances in a solution. Paper chromatography and other types of chromatography have many uses. An environmental chemist might use chromatography to identify pollutants in water, or a medical chemist to identify poison or medicines in the blood of a patient. Materials petri dish yellow food coloring ink round filter paper metric ruler pipe cleaner toothpick solvent (water, rubbing alcohol, or ethanol) WARNING: Alcohol and ethanol are flammable. Procedure 1. Add a small amount of solvent to a petri dish. 2. Use a toothpick to place a small drop of food coloring at the center of the filter paper. 3. Punch a small hole in the center of the filter paper with the toothpick. Place the pipe cleaner through this hole. 4. Carefully place the filter paper on top of the petri dish so that the end of the pipe cleaner touches the solvent. Observe what Food coloring Solvent happens as the solvent moves up the pipe cleaner and across the filter paper 5. When the solvent has finished moving, remove the filter paper from the dish. Allow the filter paper to dry. 6. Repeat steps 2 through 5, using ink instead of food coloring. Use a new pipe cleaner and filter paper. Conclude and Apply 1. Why do different bands of color appear on different areas of the filter paper? Pipe cleaner Filter paper Petri dish 2. A student used felt-tip markers to make labels for one of his collections. When water splashed on the labels, the colors began to run and smear. Use your observations from this activity to explain what happened to the writing. 3. When paper chromatography is used as an analytical tool, the solute and solvent must move only in one direction. Explain why this controlled direction is necessary to calculate the R f. Chemical Bonds 31

11 3 Enrichment The Crisscross Method The process of writing chemical formulas can be made easier by using oxidation numbers. Remember that the total charge on a compound must be zero. Remember also that oxidation numbers describe the number of electrons an atom or ion gains or loses when forming compounds. Atoms in the same group on the periodic table usually will have the same oxidation number. Use the periodic table to determine the oxidation numbers of atoms. Refer to your textbook for oxidation numbers of polyatomic ions. Example: Write the formula for barium chloride. Step 1: Determine the oxidation numbers for the two elements or ions. Because barium is in Group 2, its oxidation number is 2+. Elements in Group 2 tend to lose the two electrons in the outer energy level, leaving the ions with positive charges. Chloride is in Group 17, so its oxidation number is 1. Elements in Group 17 have seven electrons in the outer energy level and tend to gain one electron. The ions are negative. Step 2: Write the chemical symbols in the correct order, with the metal ion first. Ba Cl Now, write the oxidation numbers as superscripts. For an ion with an oxidation number of 1+ or 1, write only the sign and not the number. Ba 2 Cl Next, crisscross the numbers only not the signs this time, writing the oxidation number of one element as the subscript for the other. Don t write the number 1 here either. Step 3: Determine whether the formula is in its simplest form. Reduce the subscripts to their simplest form by dividing by a common denominator. The formula for barium chloride is BaCl 2,which cannot be further reduced. Step 4: Check the formula by calculating the total positive and total negative charges and confirming that the total charge on the compound is zero. Oxidation Number Subscript Barium (+2) (1) = +2 Chlorine ( 1) (2) = 2 Directions: Use the crisscross method to write the chemical formulas for the compounds described below. Check that the total charge on each compound equals zero. 1. Write the correct chemical formula for a compound containing barium and oxygen. What is the name of this compound? 2. Write the formula for zinc iodide, a compound that is used as an antiseptic. 3. One of the uses of ammonium sulfate is in flameproofing fabrics and paper. Write the formula for ammonium sulfate. Ba 2 Cl Ba Cl 2 32 Chemical Bonds

12 Section 1 Note-taking Worksheet Stability in Bonding A. Some elements combine chemically and no longer have the same they did before forming a compound. Chemical Bonds B. A(n) is composed of symbols and subscripts indicating the number of atoms of an element in a compound. C. Atoms form compounds when the compound is more than the separate atoms. 1. Noble gases are more than other elements because they have a complete outer energy level. 2. Elements that do not have full outer energy levels are more stable in. 3. Atoms can lose, gain, or electrons to get a stable outer energy level. 4. A(n) is the force that holds atoms together in a compound. Section 2 Types of Bonds A. A(n) is a charged particle because it has more or fewer electrons than protons. 1. When an atom an electron, it becomes a positively charged ion; a superscript indicates the charge. 2. When an atom an electron, it becomes a negatively charged ion. B. An ionic compound is held together by the the force of attraction between opposite charges of the ions. 1. The result of this bond is a(n) compound. 2. The sum of the charges on the ions in a unit of the compound is. C. are neutral particles formed as a result of sharing electrons. 1. A is the force of attraction between atoms sharing electrons. 2. Atoms can form double or triple depending on whether they share two or three pairs of electrons. 3. Electrons shared in a molecule are held to the atoms with the larger nucleus. Chemical Bonds 33

13 Note-taking Worksheet (continued) 4. A(n) molecule has one end that is slightly negative and one end that is slightly positive although the overall molecule is neutral. 5. In a(n) molecule, electrons are shared equally. Section 3 Writing Formulas and Naming Compounds A. Chemists use from the periodic table to write formulas for compounds. B. composed of two elements 1. how many electrons an atom has gained, lost, or shared to become stable 2. Use oxidation numbers and their least common multiples to write. a. When writing formulas, remember that the compound is. b. A formula must have the correct number of positive and negative ions so the charges. 3. Use the name of the first element, the root name of the second element, and the suffix ide to write the of a binary ionic compound. C. positively or negatively charged, covalently bonded group of atoms 1. The compound contains or more elements. 2. To write names, write the name of the ion first; then write the name of the ion. 3. To write, use the oxidation numbers, their least common multiple, and put parentheses around the polyatomic ion before adding a subscript. D. compound with water chemically attached to its ions E. Name binary covalent compounds by using to indicate how many atoms of each element are in the compound. 34 Chemical Bonds

14 Chapter Review Chemical Bonds Part A. Vocabulary Review Directions: Complete the sentence by writing the correct terms in the blanks. 1. An atom that has gained or lost electrons is called a(n). 2. An atom is when its outer energy level is filled with electrons. 3. A(n) tells what elements make up a compound and the ratios of the atoms of those elements. 4. A molecule that has a positive end and a negative end is a(n) molecule. 5. A bond that forms between atoms when they share electrons is a(n) bond. 6. A positive or negative number that is assigned to an element to show its combining ability in a compound is a(n). 7. A compound that is composed of only two elements is a(n). 8. A group of atoms with a positive or negative charge is a(n). 9. A(n) is a compound that has water chemically attached to its ions. 10. The force of attraction between the opposite charges of the ions in an ionic compound is a(n). 11. Molecules that do not have oppositely charged ends are molecules. 12. A(n) is formed when atoms gain, lose, or share electrons. Part B. Concept Review Directions: Place a plus sign (+) beside each statement that agrees with what was said in your textbook. Place a minus sign ( ) beside each statement that does not agree, and rewrite the statement so that it is correct. 1. Compounds have properties unlike those of their elements. 2. In a chemical formula, a subscript tells how many atoms of an element are in a unit of a compound. Assessment Chemical Bonds 37

15 Chapter Review (continued) 3. A chemical bond occurs when atoms lose, gain, or share electrons. 4. Because each noble gas has an outer energy level that is completely filled with electrons, these elements form chemical bonds easily. 5. Compounds containing polyatomic ions can have both ionic and covalent bonds. 6. A covalent bond is the force of attraction between the opposite charges of the ions in an ionic compound. 7. Neutral particles formed as a result of covalent bonding are called molecules. 8. An element that loses electrons when bonding with other atoms has a negative oxidation number. Assessment 9. When writing the formula of a compound, the symbol of the element with the positive oxidation number comes first. 10. When cobalt chloride unites with water to form cobalt hexahydrate, its formula is written CoCl 2 6H 2 O. 38 Chemical Bonds

16 1 Section Focus Transparency Activity Picking Up the Pieces Jigsaw puzzles can have hundreds even thousands of pieces. To complete the puzzle, you need to infer how each piece fits together. Size, shape, and markings all give clues as to how the pieces should be placed to make a picture. Transparency Activities 1. Where do the remaining pieces belong? How do you know? 2. How might a compound and its individual elements compare to a puzzle and its pieces? 44 Chemical Bonds

17 2 Section Focus Transparency Activity A Crystal Nature This picture shows salt crystals on the Dead Sea shore. When a salt crystal is pure, it is in the shape of a colorless cube. Impurities can make salt appear to be different colors, like white or gray. Table salt is a compound of sodium and chlorine. 1. Describe the appearance of the salt in the picture. 2. What happens to salt in water? How might you recover salt from ocean water? 3. How do people use salt? Transparency Activities Chemical Bonds 45

18 3 Section Focus Transparency Activity For Best Results, Add Water Why are these workers trying to keep the concrete wet rather than letting it dry? Concrete doesn t harden because it dries. It hardens by incorporating water into its molecular structure. If there s not enough water, the concrete won t harden properly, and it won t be very durable. Transparency Activities 1. How might construction be different in the desert compared to a rainy, temperate region? 2. What would happen if a bag of dry concrete got a little damp? What if it got very wet? 3. When a new sidewalk is finally dry, where does the water go? 46 Chemical Bonds

19 3 Teaching Transparency Common Oxidation Activity Numbers of Selected Groups 1 Hydrogen 1 H He Kr Ne Xe Lithium 3 Li Sodium 11 Na Beryllium 4 Be Magnesium 12 Mg Ar Rn Boron 5 B Aluminum 13 Al Carbon 6 C Silicon 14 Si Nitrogen 7 N Phosphorus 15 P Oxygen 8 O Sulfur 16 S Fluorine 9 F Chlorine 17 Cl Potassium 19 K Calcium 20 Ca Gallium 31 Ga Germanium 32 Ge Arsenic 33 As Selenium 34 Se Bromine 35 Br Rubidium 37 Rb Strontium 38 Sr Indium 49 In Tin 50 Sn Antimony 51 Sb Tellurium 52 Te Iodine 53 I Cesium 55 Cs Barium 56 Ba Thallium 81 Tl Lead 82 Pb Bismuth 83 Bi Polonium 84 Po Astatine 85 At Francium 87 Fr Radium 88 Ra Na Cl Na Cl Sodium Chlorine Sodium chloride Transparency Activities 0 Helium 2 He Neon 10 Ne Argon 18 Ar Krypton 36 Kr Xenon 54 Xe Radon 86 Rn Chemical Bonds 47

20 Teaching Transparency Activity (continued) 1. When does an ionic bond form between elements? 2. What is a covalent bond? 3. The formula for baking soda is NaHCO 3.Name the elements in baking soda. 4. How many pairs of electrons are shared when hydrogen and oxygen unite to form a molecule of water? 5. Using the oxidation numbers given on the transparency, write the formula for calcium chloride, a compound of calcium and chlorine. Transparency Activities 6. Write the formula for barium (Ba 2+ ) chlorate (ClO 3 ). 7. Name two pieces of information you can get from a dot diagram. 48 Chemical Bonds

21 Assessment Transparency Activity Chemical Bonds Directions: Carefully review the tables and answer the following questions. Group A Group B Water H 2 O Epsom salts Mg(OH) 2 Carbon dioxide CO 2 Sugar C 12 H 22 O 11 Ammonia NH 3 Lye NaOH Salt NaCl Baking soda NaHCO 3 Methane CH 4 Vinegar C 2 H 4 O 2 1. The compounds in Group A are different from the compounds in Group B because only the compounds in Group A. A are gases at room temperature B are used in preparing food C contain a metal and a nonmetal D contain only two different elements 2. According to the chemical formula for lye, all of the following elements are found in a lye molecule EXCEPT. F hydrogen H oxygen G nitrogen J sodium 3. According to the information contained in the tables, which compound has a total number of atoms greater than 10? A Baking soda C Sugar B Methane D Vinegar 4. According to the tables, which compound has the LEAST number of total atoms? F Ammonia H Salt G Carbon dioxide J Water Transparency Activities Chemical Bonds 49