Chapter 4 Compounds and Their Bonds. Octet Rule. Metals Form Positive Ions. Ionic and Covalent Bonds. Formation of a Sodium Ion, Na +

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1 Chapter 4 Compounds and Their Bonds Octet Rule 4.1 Octet Rule and Ions An octet Is 8 valence electrons. Is associated with the stability of the noble gases. Helium (He) is stable with 2 valence electrons (duet). Valence Electrons He 1s 2 2 Ne 1s 2 2s 2 2p 6 8 Ar 1s 2 2s 2 2p 6 3s 2 3p 6 8 Kr 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p Ionic and Covalent Bonds Metals Form Positive Ions Atoms form octets To become more stable. By losing, gaining, or sharing valence electrons. By forming ionic or covalent bonds. Metals form positive ions By a loss of their valence electrons. With the electron configuration of the nearest noble gas. That have fewer electrons than protons. Group 1A(1) metals ion 1+ Group 2A(2) metals ion 2+ Group 3A(3) metals ion Formation of a Sodium Ion, Na + Charge of Sodium Ion, Na + Sodium achieves an octet by losing its one valence electron. With the loss of its valence electron, a sodium ion has a 1+ charge. Sodium atom Sodium ion 11p + 11p + 11e - 10e

2 Formation of Negative Ions A. The number of valence electrons in aluminum is 1) 1e - 2) 2e - 3) 3e - B. The change in electrons for octet requires a 1) loss of 3e - 2) gain of 3e - 3) gain of 5e - C. The ionic charge of aluminum is 1) 3-2) 5-3) 3 + D. The symbol for the aluminum ion is 1) Al 3+ 2) Al 3-3) Al + In ionic compounds, nonmetals Achieve an octet arrangement. Gain electrons. Form negatively charged ions with 3 -, 2 -, or 1 - charges. 7 8 Formation of a Chloride Ion, Cl - Charge of a Chloride Ion, Cl - Chlorine achieves an octet by adding an electron to its valence electrons. By gaining one electron, the chloride ion has a - 1 charge. Chlorine atom Chloride ion 17p + 17p + 17e - 18e Ionic Charge from Group Numbers Some Typical Ionic Charges The charge of a positive ion is equal to its Group number. TABLE 4.1 Group 1A(1) = 1+ Group 2A(2) = 2+ Group 3A(3) = 3+ The charge of a negative ion is obtained by subtracting 8 or 18 from its Group number. Group 6A(16) = 6-8 = 2 - or = 2 -, I

3 A. Number of valence electrons in sulfur is 1) 4e - 2) 6e - 3) 8e - B. Change in electrons for octet requires a 1) loss of 2e - 2) gain of 2e - 3) gain of 4e - Chapter 4 Compounds and Their Bonds 4.2 Ionic Compounds C. Ionic charge of sulfur is 1) 2+ 2) 2-3) Ionic Compounds Ionic compounds Consist of positive and negative ions. Have attractions called ionic bonds between positively and negatively charged ions. Have high melting and boiling points. Are solid at room temperature. Salt is An Ionic Compound Sodium chloride or table salt is an example of an ionic compound Ionic Formulas Charge Balance for NaCl, Salt An ionic formula Consists of positively and negatively charged ions. Is neutral. Has charge balance. total positive charge = total negative charge The symbol of the metal is written first followed by the symbol of the nonmetal. In NaCl A Na atom loses its valence electron. A Cl atom gains an electron. The symbol of the metal is written first followed by the symbol of the nonmetal

4 Charge Balance In MgCl 2 Charge Balance in Na 2 S In MgCl 2 A Mg atom loses two valence electrons. Two Cl atoms each gain one electron. Subscripts indicate the number of ions needed to give charge balance. 19 In Na 2 S Two Na atoms lose one valence electron each. One S atom gains two electrons. Subscripts show the number of ions needed to give charge balance. 20 Writing Ionic Formulas from Charges Charge balance is used to write the formula for sodium nitride, a compound containing Na + and N 3. Na + 3 Na + + N 3 = Na 3 N Na + 3(+1) + 1(3-) = 0 Formula from Ionic Charges Write the ionic formula of the compound with Ba 2+ and Cl -. Write the symbols of the ions. Ba 2+ Cl - Balance the charges. Ba 2+ Cl - two Cl - needed Cl - Write the ionic formula using a subscript 2 for two chloride ions that give charge balance. BaCl Chapter 4 Compounds and Their Bonds Select the correct formula for each of the following ionic compounds A. Na + and S Naming and Writing Ionic Formulas 1) NaS 2) Na 2 S 3) NaS 2 B. Al 3+ and Cl - 1) AlCl 3 2) AlCl 3) Al 3 Cl C. Mg 2+ and N 3-1) MgN 2) Mg 2 N 3 3) Mg 3 N

5 Naming Ionic Compounds with Two Elements Charges of Representative Elements To name a compound with two elements Identify the cation and anion. Name the cation first followed by the name of the anion. name = metal name + stem of nonmetal name + -ide Names of Some Common Ions Complete the names of the following ions: TABLE 4.3 Ba 2+ Al 3+ K + N 3- O 2- F - P 3- S 2- Cl Examples of Ionic Compounds with Two Elements Write the names of the following compounds: Formula Ions Name cation anion 1) CaO NaCl Na + Cl - sodium chloride K 2 S K + S 2- potassium sulfide 2) KBr 3) Al 2 O 3 MgO Mg 2+ O 2- magnesium oxide 4) MgCl 2 CaI 2 Ca 2+ I - calcium iodide Al 2 O 3 Al 3+ S 2- aluminum sulfide

6 Write the formulas and names for compounds of the following ions: Br S 2 N 3 Transition Metals form Positive Ions Most transition metals and Group 4(14) metals Form 2 or more positive ions. Zn 2+, Ag +, and Cd 2+ form only one ion. Na + Al Metals that form more than One Cation The name of metals with two or more positive ions (cations) use a Roman numeral to identify ionic charge. Naming Variable Charge Metals Transition metals that form two different ions use a Roman numeral after the name of the metal ion to indicate the charge. Lead Pb 2+ lead(ii) Pb 4+ lead(iv) Naming FeCl 2 STEP 1 Determine the charge of the cation from the anion. Fe ion + 2 Cl - = Fe ion + 2- = 0 Fe ion = 2+ STEP 2 Name the cation by the element name and use a Roman numeral to show its charge. Fe 2+ = iron(ii) STEP 3 Write the anion with an ide ending. chloride STEP 4 Name cation first. iron(ii) chloride Select the correct name for each. A. Fe 2 S 3 1) iron sulfide 2) iron(ii) sulfide 3) iron (III) sulfide B. CuO 1) copper oxide 2) copper(i) oxide 3) copper (II) oxide

7 Writing Formulas Write a formula for potassium sulfide. STEP 1 Identify the cation and anion. potassium = K + sulfide = S 2 STEP 2 Balance the charges. K + S 2 K + 2(1+) + 1(2-) = 0 STEP 3 Write the cation first. 2K + and 1S 2 = K 2 S 1 = K 2 S Writing Formulas Write a formula for iron(iii) chloride. STEP 1 Identify the cation and anion. iron (III) = Fe 3+ (III = charge of 3+) chloride = Cl STEP 2 Balance the charges. Fe 3+ Cl Cl Cl (3+) + 3(1-) = 0 STEP 3 Write the cation first. 1 Fe 3+ and 3Cl = FeCl The correct formula for each of the following is: A. Copper (I) nitride 1) CuN 2) CuN 3 3) Cu 3 N Chapter 4 Compounds and Their Bonds 4.4 B. Lead (IV) oxide 1) PbO 2 2) PbO 3) Pb 2 O Some Compounds with Polyatomic Ions A polyatomic ion Is a group of atoms. Has an overall ionic charge. Some examples of polyatomic ions are NH 4 + ammonium OH hydroxide NO 3 nitrate NO 2 nitrite CO 2 3 carbonate PO 3 4 phosphate HCO 3 hydrogen carbonate (bicarbonate)

8 Some Names of Names and Formulas of Common The names of common polyatomic anions End in ate. NO 3 nitrate PO 3 4 phosphate With one oxygen less end in ite. NO 2 nitrite PO 3 3 phosphite With hydrogen attached use prefix hydrogen (or bi). HCO 3 hydrogen carbonate (bicarbonate) HSO 3 hydrogen sulfite (bisulfite) Names and Formulas of Common Naming Compounds with The positive ion is named first followed by the name of the polyatomic ion. NaNO 3 sodium nitrate K 2 SO 4 potassium sulfate Fe(HCO 3 ) 3 iron(iii) bicarbonate or iron(iii) hydrogen carbonate (NH 4 ) 3 PO 3 ammonium phosphite Some Compounds with Polyatomic Ions TABLE 4.8 Match each formula with the correct name: A. MgS 1) magnesium sulfite MgSO 3 2) magnesium sulfate MgSO 4 3) magnesium sulfide B. Ca(ClO 3 ) 2 1) calcium chlorate CaCl 2 2) calcium chlorite Ca(ClO 2 ) 2 3) calcium chloride

9 Name each of the following compounds: A. Mg(NO 3 ) 2 B. Cu(ClO 3 ) 2 C. PbO 2 D. Fe 2 (SO 4 ) 3 E. Ba 3 (PO ) 3 2 Writing Formulas with Polyatomic Ions The formula of an ionic compound Containing a polyatomic ion must have a charge balance that equals zero(0). Na + and NO 3 NaNO 3 With two or more polyatomic ions has the polyatomic ions in parentheses. Mg 2+ and 2NO 3 Mg(NO 3 ) 2 subscript 2 for charge balance Select the correct formula for each: A. aluminum nitrate 1) AlNO 3 2) Al(NO) 3 3) Al(NO 3 ) 3 B. copper(ii) nitrate 1) CuNO 3 2) Cu(NO 3 ) 2 3) Cu 2 (NO 3 ) C. iron (III) hydroxide 1) FeOH 2) FeOH 3 3) Fe(OH) 3 D. tin(iv) hydroxide 1) Sn(OH) 4 2) Sn(OH) 2 3) Sn 4 (OH) Write the correct formula for each: A. potassium bromate B. calcium carbonate C. sodium phosphate D. iron(iii) oxide E. iron (II) nitrite Name the following compounds: A. Ca 3 (PO 4 ) 2 B. FeBr 3 C. Al 2 S 3 D. Zn(NO 2 ) 2 E. NaHCO 3 Write the formulas for the following: A. calcium nitrate B. iron(ii) hydroxide C. aluminum carbonate D. copper(ii) bromide E. lithium phosphate