1 © 2006 Brooks/Cole - Thomson Kull Spring 2007 Chem 105 Lsn 4 Review: Density The density of silver is 10.5 g/cm 3. What is the volume of a piece of Ag that contains 2.8 × atoms? a cm 3 b. 53 cm 3 c. 4.8 × cm 3 d. 2.1 cm 3 What is the length of 1 side?

2 © 2006 Brooks/Cole - Thomson Kull Spring 2007 Chem 105 Lsn 4 Chemistry and Chemical Reactivity 6th Edition John C. Kotz Paul M. Treichel Gabriela C. Weaver CHAPTER 3 Molecules, Ions and Their Compounds © 2006 Brooks/Cole Thomson Lectures written by John Kotz

3 © 2006 Brooks/Cole - Thomson Kull Spring 2007 Chem 105 Lsn Molecules, Compounds, & Formulas COMPOUNDS are a combination of 2 or more elements in definite ratios by mass.COMPOUNDS are a combination of 2 or more elements in definite ratios by mass. The character of each element is lost when forming a compound.The character of each element is lost when forming a compound. MOLECULES are the smallest unit of a compound that retains the characteristics of the compound.MOLECULES are the smallest unit of a compound that retains the characteristics of the compound.

4 © 2006 Brooks/Cole - Thomson Kull Spring 2007 Chem 105 Lsn FORMULAS and 3.3 Molecular Models Glycine Molecular Formula: C 2 H 5 NO 2Molecular Formula: C 2 H 5 NO 2 Condensed FormulaCondensed Formula H 2 NCH 2 COOHto show atom ordering structural formulastructural formula Ball & stick Space-filling

5 © 2006 Brooks/Cole - Thomson Kull Spring 2007 Chem 105 Lsn Ionic compounds: Formulas, names, and Properties Ionic charges (use periodic table) –Desire for noble gas configuration –Cations (+) –Anions (-) 3.6 What charges are most commonly observed for monatomic ions of the following elements? (a)Selenium(b) fluorine (c) Iron(d) nitrogen

6 © 2006 Brooks/Cole - Thomson Kull Spring 2007 Chem 105 Lsn 4 Charges on Common Ions By losing or gaining e-, atom has same number of e-’s as nearest Group 8A atom.

7 © 2006 Brooks/Cole - Thomson Kull Spring 2007 Chem 105 Lsn 4 IONIC COMPOUNDS NH 4 + Cl - ammonium chloride, NH 4 Cl Name derived by adding -ide to stem

8 © 2006 Brooks/Cole - Thomson Kull Spring 2007 Chem 105 Lsn 4 Note: many O containing anions have names ending in –ate (or -ite). Table 3.1, page 107.

9 © 2006 Brooks/Cole - Thomson Kull Spring 2007 Chem 105 Lsn 4 Some Ionic Compounds Mg 2+ + NO > Mg(NO 3 ) 2 magnesium nitrate Fe 2+ + PO > Fe 3 (PO 4 ) 2 iron(II) phosphate (See CD, Screen 3.11 for naming practice) calcium fluoride Ca F - ---> CaF 2

10 © 2006 Brooks/Cole - Thomson Kull Spring 2007 Chem 105 Lsn 4 Properties of Ionic Compounds Forming NaCl from Na and Cl 2 A metal atom can transfer an electron to a nonmetal.A metal atom can transfer an electron to a nonmetal. The resulting cation and anion are attracted to each other by electrostatic forces.The resulting cation and anion are attracted to each other by electrostatic forces. These forces are governed by COULOMB’S LAW.These forces are governed by COULOMB’S LAW.

11 © 2006 Brooks/Cole - Thomson Kull Spring 2007 Chem 105 Lsn 4 Electrostatic Forces COULOMB’S LAW Active Figure 3.10

12 © 2006 Brooks/Cole - Thomson Kull Spring 2007 Chem 105 Lsn 4 Importance of Coulomb’s Law NaCl, Na + and Cl -, m.p. 804 o C MgO, Mg 2+ and O 2- m.p o C

13 © 2006 Brooks/Cole - Thomson Kull Spring 2007 Chem 105 Lsn 4 NONMETALSNONMETALS NONMETAL + n e > X n- where n = 8 - Group no. C 4-,carbide N 3-, nitride O 2-, oxide S 2-, sulfide F -, fluoride Cl -, chloride Group 7AGroup 6A Group 4A Group 5A Br -, bromide I -, iodide Name derived by adding -ide to stem

14 © 2006 Brooks/Cole - Thomson Kull Spring 2007 Chem 105 Lsn For each of the following compounds, give the formula, charge, and the number of each ion that makes up the compound. (a)K 2 S (b)CoSO 4 (c)CuCO 3 (d)Ti(SO 4 ) 2 (e)KH 2 PO 4

15 © 2006 Brooks/Cole - Thomson Kull Spring 2007 Chem 105 Lsn Platinum is a transition element and forms Pt 2+ and Pt 4+ ions. Write the formulas for the compounds of each of these ions with (a) chloride ions and (b) sulfide ions.

16 © 2006 Brooks/Cole - Thomson Kull Spring 2007 Chem 105 Lsn 4 CH 4 methane BCl 3 boron trichloride CO 2 Carbon dioxide All are formed from two or more nonmetals. Ionic compounds generally involve a metal and nonmetal (NaCl) 3.4 Molecular Compounds Compounds without Ions

17 © 2006 Brooks/Cole - Thomson Kull Spring 2007 Chem 105 Lsn 4 ELEMENTS THAT EXIST AS MOLECULES Allotropes of C

18 © 2006 Brooks/Cole - Thomson Kull Spring 2007 Chem 105 Lsn 4 ELEMENTS THAT EXIST AS DIATOMIC MOLECULES

19 © 2006 Brooks/Cole - Thomson Kull Spring 2007 Chem 105 Lsn 4 ELEMENTS THAT EXIST AS POLYATOMIC MOLECULES White P 4 and polymeric red phosphorus S 8 sulfur molecules

20 © 2006 Brooks/Cole - Thomson Kull Spring 2007 Chem 105 Lsn Formulas, Compounds, and the mole grams/moles/somethings a) Molar mass of C 2 H 6 O = g/mol (b) Calc. moles of alcohol How many moles of alcohol are there in a “standard” can of beer if there are 21.3 g of C 2 H 6 O? How many molecules of alcohol are there in a “standard” can of beer if there are 21.3 g of C 2 H 6 O? = 2.78 x molecules

21 © 2006 Brooks/Cole - Thomson Kull Spring 2007 Chem 105 Lsn 4 How many atoms of C are there in a “standard” can of beer if there are 21.3 g of C 2 H 6 O? = 5.57 x C atoms There are 2.78 x molecules. Each molecule contains 2 C atoms. Therefore, the number of C atoms is

22 © 2006 Brooks/Cole - Thomson Kull Spring 2007 Chem 105 Lsn Give the formula for each of the following ionic compounds. (a)Calcium hydrogen carbonate (b)Potassium permanganate (c)Magnesium perchlorate (d)Potassium hydrogen phosphate (e)Sodium sulfite

23 © 2006 Brooks/Cole - Thomson Kull Spring 2007 Chem 105 Lsn Calculate the molar mass of each hydrated compound. Note that the water of hydration is included in the molar mass. (a)H 2 C 2 O 4  2 H 2 O (b)MgSO 4  7 H 2 O

24 © 2006 Brooks/Cole - Thomson Kull Spring 2007 Chem 105 Lsn Assume you have mol of each of the following compounds. What mass of each is present? (a) C 14 H 10 O 4, benzoyl peroxide (b) Pt(NH 3 ) 2 Cl 2, cisplatin

25 © 2006 Brooks/Cole - Thomson Kull Spring 2007 Chem 105 Lsn The compound (NH 4 ) 2 SO 4 consists of two polyatomic ions. What are the names and electric charges of these ions? What is the molar mass of this compound?

26 © 2006 Brooks/Cole - Thomson Kull Spring 2007 Chem 105 Lsn 4 68

27 © 2006 Brooks/Cole - Thomson Kull Spring 2007 Chem 105 Lsn 4 88