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Chemistry 103OutlineIonic vs. CovalentNomenclature - Naming CompoundsPeriodic Table and Some IonsLearning CheckPolyatomic IonsSlide 8Slide 9Molecules and Covalent CompoundsDiatomic ElementsElectron-Dot Diagrams (Lewis Structures)Multiple Bonds in N2Lewis Structures continued…Properties of BondsLewis Dot StructuresLewis Dot Structures extendedDrawing Lewis StructuresDrawing Lewis Structures, continuedDrawing Lewis Structures, continued…Slide 21Slide 22Slide 23Resonance StructuresLewis Dot StructureSlide 26NOMENCLATURESlide 28Naming Covalent CompoundsNaming Binary Covalent CompoundsGreek PrefixesNaming Covalent CompoundsSlide 33Common NamesSlide 35Hydrogen First in compoundChemistry 103Lecture 11OutlineI. Ionic Compounds (in review)II. Covalent CompoundsLewis Dot Diagrams/Lewis structuresProperties predictedNomenclatureBond PolarityIonic vs. CovalentNaCl (sodium chloride) CH4 (methane)Nomenclature - Naming CompoundsFIRST QUESTION: IONIC or COVALENT????IONIC NOMENCLATURE RULES (Metal + Nonmetal)Periodic Table and Some Ions Copyright © 2005 by Pearson Education, Inc.Publishing as Benjamin Cummings6Learning CheckSelect the correct name for each:1. Fe2S3 A) iron sulfide B) iron(II) sulfide C) iron (III) sulfide2. CuO A) copper oxide B) copper(I) oxide C) copper (II) oxidePolyatomic IonsPolyatomic ionAn ion formed from a group of atoms (held together by covalent bonds) through loss or gain of electronsCan be the positive or the negative ion in an ionic compound8Learning CheckName the following compounds:A. Ca3(PO4)2Calcium PhosphateB. FeBr3Iron (III) BromideC. Al2S3Aluminum SulfideD. MgSO4Magnesium Sulfate9Learning CheckWrite the formulas for each of the following:A. calcium nitrate Ca(NO3)2B. iron(II) hydroxide Fe(OH)2C. aluminum carbonate Al2(CO3)3D. lithium phosphate Li3PO4Molecules and Covalent Compounds11Diatomic Elements•These elements share electrons to form diatomic, covalent molecules.Electron-Dot Diagrams (Lewis Structures)Electron-dot diagrams show•The order of bonded atoms in a covalent compound.•The bonding pairs of electrons between atoms.•The unshared (lone) valence electrons. (nonbonding)•A central atom with an octet.Copyright © 2008 by Pearson Education, Inc.Publishing as Benjamin CummingsMultiple Bonds in N2In nitrogen N2,•Octets are achieved by sharing three pairs of electrons, which is a triple bond.Copyright © 2008 by Pearson Education, Inc.Publishing as Benjamin CummingsLewis Structures continued…H2OC2H4C2H2Properties of BondsBond Length Distance between 2 nucleiTriple bond < Double Bond < Single BondBond StrengthEnergy required to separate 2 nucleiTriple bond > Double Bond > Single BondLewis Dot StructuresExample: CO:C : : : O:Coordinate Covalent Bonds - bond in which there is an uneven contribution of the shared electron pairs.Lewis Dot Structures extendedAs long as all the atoms in your molecule are satisfied under the octet rule (exception is H with only 2 electrons), then you have an acceptable Lewis Dot Structure.Not always easy to decide how to position electrons in a molecule to form the “stable 8” configuration for each atom.Drawing Lewis StructuresExample: SO31. Determine the arrangement of the atoms in the molecule. (Symmetry is key - first atom usually is the central atom unless it is an H) O S O ODrawing Lewis Structures, continued2. Determine the total number of valence electrons present. O S O OS = 6 valence electronsO = 6 valence electrons x 3 = 18TOTAL = 24Drawing Lewis Structures, continued…3. Determine the total number of valence electrons the molecule (or ion) will need to have a noble gas configuration.Nobel Gas CountH 2 S, O, F, … 8Drawing Lewis Structures, continued…3. Determine the total number of valence electrons the molecule (or ion) will need to have a noble gas configuration. O S O OValence count = 24Noble Gas count = 8 x 4 = 32Drawing Lewis Structures, continued…4. Determine the number of bonding electron pairs needed:Noble Gas count (step 3) - Valence (step 2) 2= Total number of bondsSO332 - 24 = 4 bonds 2Drawing Lewis Structures, continued…5. Write in the skeletal structure, the bonding electron pairs and the nonbonding pairs of electrons to satisfy octet rule.6. Check the electron dot structure to confirm that the total number of electrons present is the same as the valence count in step 2THIS ONLY WORKS FOR SYSTEMS THAT FOLLOW THE OCTET RULE - NO EXCEPTIONS!!!!Resonance StructuresTwo or more Lewis Dot structures that have the same arrangement of atoms and the same number of electrons, but differ in the location of the electrons (bonds)Lewis Dot StructureDraw the Lewis Dot Structure for Nitrate (NO3-)Resonance structures for NO3− are − - - − - - − :O: :O: :O: ║ │ │ N N N :O : :O: :O: :O : :O: :O: - - - - - - - - Resonance StructuresNOMENCLATURENaming covalent compoundsNomenclature - Naming CompoundsFIRST QUESTION: IONIC or COVALENT???? IONIC RULES COVALENT RULES(Metal + Nonmetal) (Nonmetals)Naming Covalent Compounds Covalent CompoundsGreek Prefixes Common Names H-first(BINARY = 2 ELEMENTS)Naming Binary Covalent CompoundsFirst word of name:Greek prefix + name of first elementNote: if the prefix would be “mono” for the first element, the prefix is not includedNote: when an element name begins with a vowel, an a or o at the end of the Greek prefix is dropped for phonetic reasonsSecond word of nameGreek prefix + stem of name of second element with “-ide” endingGreek PrefixesTable in text1 mono 6 hexa2 di 7 hepta3 tri 8 octa4 tetra 9 nona5 penta 10 decaNaming Covalent CompoundsExamples:P4O10CO CO2NCl3 N2O5Naming Covalent Compounds Covalent CompoundsGreek Prefixes Common Names H-firstCommon NamesH2O waterH2O2hydrogen peroxideCH4methaneNH3ammoniaPH3phosphineNaming Covalent Compounds Covalent CompoundsGreek Prefixes Common Names H-firstHydrogen First in compoundHCl hydrogen chlorideH2SO4hydrogen sulfateH3PO4hydrogen phosphate When in water (aq) has very different properties – ACIDSHCl(aq) hydrochloric acidH2SO4(aq) Sulfuric AcidH3PO4(aq) Phosphoric


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UNLV CHEM 103 - Lecture 11

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