Section 3.1 Review Answers (Student textbook page 109)

Transcription

1 pathways for a variety of scientists and technicians. The development, maintenance, and applications of the equipment for future science discovery not only will help us develop cleaner technologies for future use, but also will allow us to deal with some of the messes left behind by older technologies. As we move forward, new technologies will lead to new discoveries and new discoveries will lead to new technologies. Section 3.1 Review Answers (Student textbook page 109) Checking Concepts 1. Chlorine has toxic properties that make it useful as a disinfectant but a hazard to human health if used improperly. 2. HHPS stands for Hazardous Household Product Symbols. The upside-down triangle means that the container is dangerous. The octagon means that the contents of the container are dangerous. The explosion symbol means the container may explode. The symbol showing bones in a hand immersed in liquid means the product can burn human tissue. The flame symbol means the product or its fumes will catch fire easily. The skull and crossbones symbol means the product is poisonous. 3. Chemists classify compounds as ionic or molecular. Ionic compounds are made of ions and molecular compounds are made of molecules. These compounds have characteristic properties. For example, ionic compounds conduct electric current when dissolved in water while molecular compounds do not. 4. An atom is electrically neutral. An ion is a charged atom or group of atoms. 5. Ice cream, hand sanitizer, a plastic bottle, air, and paper all contain chemical compounds. 6. Sample answer: Properties of Ionic and Molecular Compounds Ionic Compounds Molecular Compounds melting and boiling points ability to conduct electric current hardness or softness high conduct electric current in liquid or when dissolved, not as solid tend to be hard and brittle and break along straight lines low, in general do not conduct solids tend to be soft 7. The covalent bonds in molecular compounds and the ionic bonds in ionic compounds are very strong. However, covalent bonds are formed when atoms share electrons and ionic bonds are formed when atoms transfer electrons, creating oppositely charged ions that are then attracted to one another. 8. Ionic compounds are neutral because the positive charges and negative charges of the ions are perfectly balanced. 9. The 3 means that atoms of the element tend to form ions with charges of 3 in ionic compounds. Understanding Key Ideas 10. The term lattice structure describes the regular, repeating pattern in which ions, such as sodium and chloride ions, are arranged in an ionic compound such as sodium chloride. 11. For electric current to be conducted, there must be a source of mobile charges. In solid calcium chloride, the calcium ions and chloride ions are held tightly in a lattice TR-2-28 MHR Unit 2 Chemical Reactions

2 Answers to Check Your Understanding Questions (Student textbook page 113) 7. Atoms of elements in Group 17 form ions with a charge of 1. Atoms of elements in Group 16 form ions with a charge of 2. Atoms of elements in Group 15 form ions with a charge of (a) Binary; it consists of two elements only Binary; it consists of two elements only Not binary; it consists of three elements Not binary; it consists of three elements 9. (a) rubidium bromide magnesium oxide strontium fluoride 10. (a) potassium bromide magnesium chloride magnesium selenide sodium sulfide lithium nitride aluminum bromide (g) beryllium fluoride rubidium bromide Answers to Practice Problems (Student textbook page 115) 1. (a) NaBr K 2 S ZnI 2 Mg 3 N 2 2. (a) NaI ZnO MgCl 2 K 2 Se Ag 2 S AlI 3 (g) AlP CaO (i) CaS (j) RbBr 3. The chemical formula of silver iodide is AgI. Answer to Caption Question Figure 3.14 (Student textbook page 116): The colour difference of the two samples indicates that they are two different compounds with different properties. Answers to Check Your Understanding Questions (Student textbook page 117) 11. (a) vanadium(iv) Chapter 3 Chemical Names, Formulas, and Equations MHR TR-2-33

3 nickel(iii) gold(i) titanium(iv) 12. (a) NiCl 3 PbS 2 Cu 2 O CuO Answers to Practice Problems (Student textbook page 117) 4. (a) cobalt(iii) oxide manganese(iv) sulfide copper(ii) chloride copper(i) chloride 5. (a) iron(ii) oxide copper(i) nitride tin(iv) sulfide tin(ii) nitride nickel(iii) sulfide nickel(ii) sulfide (g) lead(iv) fluoride titanium(iv) sulfide Answer to Caption Question Figure 3.17 (Student textbook page 118): Shellfish get calcium ions and carbonate ions from the amino acids in the organisms they eat and from dissolved salts in seawater. Answers to Practice Problems (Student textbook page 119) 6. (a) Ba(NO 3 ) 2 K 2 CO 3 NiSO 4 Mg 3 (PO 4 ) 2 Na 2 Cr 2 O 7 FeCrO 4 (g) Pb(CH 3 COO) 4 (NH 4 ) 2 SO 4 7. (a) The formula shows phosphide, not phosphate as the negative ion. The correct formula is Na 3 PO 4. The formula is missing parentheses around the nitrate ion. The correct formula is Mg(NO 3 ) 2. The formula is missing the subscript 2 for the potassium ion. The correct formula is K 2 SO 3. The formula has unnecessary parentheses around the hydroxide ion. The correct formula is NaOH. 8. CaSO 4 TR-2-34 MHR Unit 2 Chemical Reactions

4 5. For an ionic compound, the chemical formula represents the ratio of the ions in the compound. The ratio 3:6 can be further reduced to 1:2 so the formula should be written as CaF Of the compounds given, the following are binary compounds: AlCl 3, H 2 O, MgS, and PbF (a) silver chloride, AgCl zinc oxide, ZnO beryllium iodide, BeI 2 magnesium fluoride, MgF 2 8. (a) You need to know which ion of iron is part of the oxide. You would probably be given this information through the name of the iron ion, that is, iron(ii) or iron(iii). 10. Mercury could form mercury(i) oxide, HgO 2, or mercury(ii) oxide, HgO. Understanding Key Ideas 11. Both sodium and magnesium atoms tend to lose electrons to atoms of other elements and form positive ions when they form ionic compounds. 12. Electron accounting is a helpful way to think of writing formulas for ionic compounds because you need to ensure that the final formula represents a neutral compound. You need to keep track of the electrons lost by the positive ions and the electrons gained by the negative ions. The ions are present in such a ratio that the lost column equals the gained column, just as in accounting. 13. The name copper(ii) chloride is correct. The ionic compound that contains a ratio of 1 copper ion to 2 chloride ions must contain the copper(ii) ion for the charges to balance. 14. (a) Fe 3 N 2 PbO Cu 2 S SnF (a) NO 2 SO 3 N 2 O 4 PCl (a) aluminum phosphate sodium carbonate potassium hydrogen carbonate magnesium hydroxide 17. (a) Na 2 SO 4 Mg 3 (PO 4 ) 2 Ca(NO 3 ) 2 Al(ClO 2 ) (a) CuClO 3 Fe 3 (PO 4 ) 2 TR-2-40 MHR Unit 2 Chemical Reactions

5 Sn(CO 3 ) 2 Ni(MnO 4 ) 2 Project Prep Sample answer: Using systematic names and formulas in the planning and analysis of a scientific investigation is vitally important because in the absence of agreed-upon nomenclature and formula-writing conventions, scientists could not communicate their results clearly and unambiguously to their peers in the global scientific community. Acceptable student answers will reflect this key advantage of using systematic names and formulas Chapter 3 Chemical Names, Formulas, and Equations MHR TR-2-41