2 4.1 Octet Rule and Ions He 2 2 Ne 2, 8 8 Ar 2, 8, 8 8 An octet is 8 valence electrons.is associated with the stability of the noble gases.He is stable with 2 valence electrons (duet).valence electronsHeNe 2,Ar 2, 8,Kr 2, 8, 14,
3 Ionic and Covalent Bonds Atoms that are not noble gases form octetsto become more stable.by losing, gaining, or sharing valence electrons.by forming ionic bonds or covalent bonds.
4 Metals Form Positive Ions (Cations) by a loss of their valence electrons.with the electron configuration of the nearest noble gas.that have fewer electrons than protons.Called cationsGroup 1A metals ion 1+Group 2A metals ion 2+Group 3A metals ion 3+
7 Charge of Magnesium Ion, Mg2+ With the loss of two valenceelectrons, magnesium forms apositive ion with a 2+ charge.Mg atom Mg2+ ion12p+ 12p+12e e-
8 ExamplesA. 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) a 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) Al3+. 2) Al3-. 3) Al+.
9 Formation of Negative Ions (Anions) In ionic compounds, nonmetals in Groups 5A (15), 6A (16) and 7A (17)achieve an octet arrangement by gaining electrons.form negatively charged ions with 3-, 2-, or 1- charges.called anions
10 Formation of a Chloride, Cl- Chlorine achieves an octet by adding an electron to its valence electrons.
12 Ionic Charge from Group Numbers The charge of a positive ion is equal to its Group number.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) = = 2-or = 2-
14 ExamplesA. The number of valence electrons in phosphorous is 1) 4e-. 2) 5e-. 3) 8e-. B. The change in electrons for octet requires a 1) loss of 2e-. 2) gain of 2e-. 3) a gain of 3e-. C. The ionic charge of sulfur is 1) 2+. 2) 3-. 3) 4-.
15 4.2 Ionic Compounds Ionic compounds Sodium chloride or “table salt” is an example of an ionic compound.Ionic compoundsconsist 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.
16 Ionic Formulas An ionic formula consists of positively and negatively charged ions.is neutral.has charge balance.total positive charge = total negative chargeThe symbol of the metal is written first, followed by the symbol of the nonmetal.
17 Charge Balance for NaCl, “Salt” 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.
18 Charge Balance in MgCl2 In MgCl2, a Mg atom loses 2 valence electrons. two Cl atoms each gain 1 electron.subscripts indicate the number of ions needed to give charge balance.
19 Charge Balance in Na2S In Na2S, two Na atoms lose 1 valence electron each.one S atom gains 2 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 forsodium nitride, a compound containing Na+ and N3−.Na+3 Na N3− = Na3N3(+1) (3-) =
21 Formula from Ionic Charges Write the ionic formula of the compound with Ba2+ and Cl.Write the symbols of the ions.Ba2+ ClBalance the charges.Ba2+ Cl two Cl- needed ClWrite the ionic formula using a subscript 2 fortwo chloride ions.BaCl2
22 ExamplesSelect the correct formula for each of the following ionic compounds. A. Na+ and O2- 1) NaO 2) Na2O 3) NaO2 B. Mg2+ and Cl- 1) MgCl2 2) MgCl 3) Mg2Cl C. Al3+ and O2- 1) AlO 2) Al2O3 3) Al3O2
23 Naming Ionic Compounds with Two Elements 4.3 Naming and Writing Ionic FormulasNaming Ionic Compounds with Two ElementsTo name a compound that contains two elements,identify the cation and anion.name the cation first, followed by the name of the anion with an –ide ending.
24 ExamplesComplete the names of the following ions: Ca2+ Al3+ Li+ _________ __________ _________ N3 Se2 F _________ __________ _________ P3 S2 Br
25 Examples of Ionic Compounds with Two Elements Formula Ions Namecation anionNaCl Na Cl- sodium chlorideK2S K S2- potassium sulfideMgO Mg O2- magnesium oxideCaI2 Ca I- calcium iodideAl2O3 Al O2- aluminum oxide
26 ExamplesWrite the formulas and names for compounds of the following ions:Br− S2− N3−Li+Al3+
27 ExampleWrite the formula and names of the following compounds: 1) K+ and Br- 2) Ca2+ and O2- 3) Al3+ and S2- 4) Mg2+ and F-
28 Transition Metals Form Positive Ions Most transition metals and Group 4 (14) metals form 2 or more positive ions. However, Zn2+, Ag+, and Cd2+ form only one ion.
29 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.
30 Naming FeCl2To name FeCl2: 1. Determine the charge of the cation using the charge of the anion (Cl-). Fe ion + 2 Cl- = Fe ion + 2- = 0 Fe ion = Name the cation by the element name and add a Roman numeral in parentheses to show its charge. Fe2+ = iron(II) 3. Write the anion with an ide ending. FeCl2 = iron(II) chloride
31 Naming Cr2O3To name Cr2O3: 1. Determine the charge of cation from the anion (O2-). 2 Cr ions + 3 O2- = 0 2 Cr ions + 3 (2-) = 0 2 Cr ions - 6 = 0 2 Cr ions = 6+ Cr ion = 3+ = Cr3+ 2. Name the cation by the element name and add a Roman numeral in parentheses to show its charge. Cr3+ = chromium(III) 3. Write the anion with an ide ending. chromium(III) oxide = Cr2O3
32 ExamplesSelect the correct name for each. A. Fe2S3 1) iron sulfide 2) iron(II) sulfide 3) iron(III) sulfide B. CuO 1) copper oxide 2) copper(I) oxide 3) copper(II) oxide
33 Writing FormulasWrite a formula for potassium sulfide. 1. Identify the cation and anion. potassium = K+ sulfide = S2− 2. Balance the charges. K+ S2− K+ 2(1+) + 2(1-) = K+ and 1 S2− = K2S
34 Writing FormulasWrite a formula for iron(III) chloride. 1. Identify the cation and anion. iron (III) = Fe3+ (III = charge of 3+) chloride = Cl− 2. Balance the charges. Fe3+ Cl− Cl− = (3+) + 3(1-) = 0 Cl− 3. 1 Fe3+ and 3 Cl− = FeCl3
35 ExamplesWhat is the correct formula for each of the following? A. Copper(I) nitride 1) CuN 2) CuN3 3) Cu3N B. Lead(IV) oxide 1) PbO2 2) PbO 3) Pb2O4
36 4.4 Polyatomic Ions A polyatomic ion is a group of atoms. has an overall ionic charge.Some examples of polyatomic ions areNH4+ ammonium OH− hydroxideNO3− nitrate NO2− nitriteCO32− carbonate PO43− phosphateHCO3− hydrogen carbonate(bicarbonate)
38 Some Names of Polyatomic Ions The names of common polyatomic anionsend in ate.NO3− nitrate PO43− phosphatewith one oxygen less end in ite.NO2− nitrite PO33− phosphitewith hydrogen attached use the prefix hydrogen (or bi).HCO3− hydrogen carbonate (bicarbonate)HSO3− hydrogen sulfite (bisulfite)
39 Names and Formulas of Common Polyatomic Ions Memorize these ions
40 Naming Compounds with Polyatomic Ions The positive ion is named first, followed by the name of the polyatomic ion.NaNO3 sodium nitrateK2SO4 potassium sulfateFe(HCO3)3 iron(III) bicarbonateor iron(III) hydrogen carbonate(NH4)3PO3 ammonium phosphite
41 ExamplesMatch each formula with the correct name. A. MgS 1) magnesium sulfite MgSO3 2) magnesium sulfate MgSO4 3) magnesium sulfide B. Ca(ClO3)2 1) calcium chlorate CaCl2 2) calcium chlorite Ca(ClO2)2 3) calcium chloride
42 Examples Name each of the following compounds: A. Mg(NO3)2 B. Cu(ClO3)2C. PbO2D. Fe2(SO4)3E. Ba3(PO3)2
43 Writing Formulas with Polyatomic Ions The formula of an ionic compoundcontaining a polyatomic ion must have a charge balance that equals zero (0).Na+ and NO3− -> NaNO3with two or more polyatomic ions has the polyatomic ions in parentheses.Mg2+ and 2NO3− -> Mg(NO3)2subscript 2 for charge balance
44 ExamplesSelect the correct formula for each. A. aluminum nitrate 1) AlNO3 2) Al(NO)3 3) Al(NO3)3 B. copper(II) nitrate 1) CuNO3 2) Cu(NO3)2 3) Cu2(NO3) C. iron(III) hydroxide 1) FeOH 2) Fe3OH 3) Fe(OH)3 D. tin(IV) hydroxide 1) Sn(OH)4 2) Sn(OH)2 3) Sn4(OH)
45 Examples Write the correct formula for each. A. potassium bromate B. calcium carbonateC. sodium phosphateD. iron(II) nitrite