5The Octet Rule 2 valence electrons He 2 valence electrons Li
6Ionic BondsIonic bonds are a type of chemical bond based on electrostatic forces between two oppositely-charged ions.It is basically the transfer of one electron from one atom to another
7Ionic BondsAn ion is an atom or group of atoms that have a charge. Atoms normally have a neutral charge because most often they have the same number of electrons and protons. They become ions by the loss or addition of one or more electrons. This process is called ionization.
8Ionic BondsAn ion that has more electrons than protons is called an anion, and an ion that has fewer electrons than protons is called a cation.
9Ionic BondsThe name ion was given by a man named Michael Faraday, which comes from a Greek word meaning “to go” or “a goer”.The word anion comes from the Greek word meaning (a thing) “going up” and cation means (a thing) “going down”.
10Ionic CompoundsIonic compound (salt) – compound made of cations and anions.cations are formed from metalsanions are formed from non-metalsIonic bond – the force that holds an ionic substance together.
12Ionic bonds Occurs when: 1. a metal atom loses an electron and becomes a positive ion2. a non-metal atom gains the electron and becomes a negative ion3. the positive and negative attract each other and form a bond
13Ionic Bonding+-IMPORTANT: Although the ions in a salt are charged, the compound as a whole is not.
14How do ionic bonds form Use the criss-cross method Step 1- Identify the metal and non-metalStep 2- Write the symbolsStep 3- write the chargesStep 4- cross over the chargesStep 5- remove the charge (+ -)Step 6- simplify the numbers and get rid of 1’sNOTE: THE OVERALL CHARGE ON IONIC FORMULAS SHOULD ALWAYS EQUAL ZERO!!!!!!
15Ionic FormulasChemical formula – indicates the number and type of atoms in a substance.H2O2 hydrogen atoms + 1 oxygen atomNaNO31 sodium ion + 1 nitrogen atom + 3 oxygen atomsFormula unit – lowest whole-number ratio of ions in a compound.The formula unit for table salt is NaCl.1 unit of Na+ ions per 1 unit of Cl- ions.Formula does not show the charges of the ions.
16Ionic Formulas What salt forms when aluminum combines with chlorine? Aluminum has 3 valence electrons.Loses 3 e- to reach octet.Forms Al+3 ion.Chlorine has 7 valence electrions.Gains 1 e- to reach octet.Forms Cl-1 ion.If the compound is neutral, it will take 1 Al+3 ion for every 3 Cl-1 ions.The formula is AlCl3.
18Ionic Bonds – Writing Formulas CRISS-CROSS METHODOxidation numbers (excluding charge) of each ion trade places to become the subscripts in the formula – must be reduced to lowest whole number ratio; 1’s are not writtenCa & SCa2S2Al & ClAlCl3CaS18
19Writing Ionic Formulas Criss-Cross Method of writing ionic formulas:Criss-cross charges to become subscriptsDrop the charges when crossing over.Example: What salt is formed from sodium and sulfur?Na forms +1 ions.S forms -2 ions.Na+1 + S-2 Na2S
21Writing Ionic Formulas If the subscripts can be reduced, do so.Example: calcium + oxygenIons: Ca+2 + O-2Wrong: Ca2O2Right: CaOExample: lead + oxygenIons: Pb+4 + O-2Wrong: Pb2O4Right: PbO2
22Ionic Bonds – Writing Formulas Sodium and chlorine bond in a 1:1 ratio to form NaClCalcium and chlorine bond in a 1:2 ratio for form CaCl2What determines each ratio & formula? ________________oxidation numbers
23Ionic Bonds – Writing Formulas Try to predict the ratio and resulting formula for each of the following ions based on their oxidation numbers:IonsOxidation NumbersRatioFormulaMagnesium & OxygenMg2+ & O2-1:1MgOLithium &SulfurAluminum & OxygenSodium & PhosphorusBarium &FluorineLi+ & S2-2:1Li2SAl3+ & O2-2:3Al2O3Na+ & P3-3:1Na3PBa2+ & F-1:2BaF2
24We will learn how to write nomenclature for: Ternary Salts3 or more elementsIncludes a polyatomic ionSalts with Multiple Oxidation NumbersCan be binary or ternaryIncludes a transition metal
25Polyatomic Ions Polyatomic Ions – ions made of more than one atom. Examples:NO3-11 nitrogen atom and 3 oxygen atoms that collectively have a -1 charge.SO4-21 sulfur atom and 4 oxygen atoms that collectively have a -2 charge.PO4-31 phosphorus atom and 4 oxygen atoms that collectively have a -3 charge.NH4+11 nitrogen atom and 4 hydrogen atoms that collectively have a +1 charge.
26Polyatomic Ions in Salts Treat them like single-atom ions.But do not change their formula!If you need more than one of a particular polyatomic ion, use parentheses.Example:Na+1 + NO3-1 NaNO3Mg+2 + NO3-1 Mg(NO3)2Al+3 + NO3-1 Al(NO3)3
28NameFormulaacetateC2H3O2- or CH3COO-ammoniumNH4+carbonateCO32-chlorateClO3-chloriteClO2-chromateCrO42-cyanideCN-dichromateCr2O72-hydrogen carbonateHCO3-hydroxideOH-hypochloriteClO-nitrateNO3-nitriteNO2-perchlorateClO4-permanganateMnO4-phosphatePO43-sulfateSO42-sulfiteSO32-Polyatomic IonsSome ions contain more than one element - called a polyatomic ionThe group as a whole has an overall chargeExamples:Lithium and sulfate would bond together to make Li2SO4Ammonium and sulfur would bond together to make (NH4)2S
29Ternary Salt NamingContains 3 or more elements: cation & anion – most polyatomic ions are anions, only cation is ammonium (NH4+)Naming:Name the cation (no changes)Name the anion (no changes)Example: Na2SO4 = sodium sulfateException: When ammonium is paired with an element anionNH4Cl = ammonium chloride
30Al & SO3 Al2(SO3)3 K & PO4 K3PO4 Ternary Salt Formulas + 3- 3+ 2- You must use parentheses if you have more than one polyatomic ion. Be sure to criss-cross the oxidation numbers and write it OUTSIDE of the parentheses.Al & SO3Al2(SO3)3K & PO4K3PO430
31Ternary Salt Formulas & Naming Try to predict the formulas and names for each ternary salt:IonsOxidation NumbersRatioFormulaNamePotassium & HydroxideK+ & OH-1:1KOHpotassium hydroxideCalcium & CarbonateBarium &NitrateSodium & PhosphateAmmonium & SulfurCa2+ & CO32-1:1CaCO3calcium carbonateBa2+ & NO3-2:1Ba(NO3)2barium nitrateNa3PO4Na+ & PO43-1:3sodium phosphateNH4+ & S2-1:2(NH4)2Sammonium sulfide
32Salts with Multiple Oxidation #s Naming Transition elements can form more than one type of positive ion.For example, copper can form both Cu+ and Cu2+ ions, and iron can form both Fe2+ and Fe3+ ions.Zinc and silver are two exceptions – they only have one oxidation numberThe zinc ion is Zn2+ and the silver ion is Ag+.
33Salts with Multiple Oxidation #s Naming Transition elements can form more than one type of positive ion.Naming:Name the cationPut the roman numeral representing the oxidation # of the metal in parentheses (do not indicate the charge)Name the anion, changing the ending to “ide” (binary) or naming the polyatomic ion (ternary)Example:FeCl2 = iron (II) chlorideFeCl3 = iron (III) chloride
34Salts with Multiple Oxidation Numbers Practice IonsOxidation NumbersRatioFormulaNameCopper & NitrateCu+ & NO3-1:1CuNO3copper (I) nitrateLead &OxygenCobalt &HydroxideNickel & PhosphateChromium & SulfurPb4+ & O2-2:1PbO2lead (IV) oxideCo3+ & OH-3:1Co(OH)3cobalt (III) hydroxideNi2+ & PO43-2:3Ni3(PO4)2nickel (II) phosphateCr2+ & S2-1:1CrSchromium (II) sulfide