2atoms that stay together Chemical BondingIonic Bonds: atoms give up or gain e– andare attracted to each other bycoulombic attractionloses e–gains e–NaNa+ClCl–Na+ + Cl–NaClionic compounds = saltsK+ + NO3–KNO3where NO3– is a polyatomic ion:a charged group ofatoms that stay together
3Properties of Salts 1. very hard each ion is bonded to several oppositelycharged ions2. high melting pointsmany bonds must bebroken3. brittlewith sufficient force,like atoms arebrought next toeach other and repelcalcite
4(i.e., cations and anions) Writing Formulas of Ionic Compoundschemical formula:has neutral charge;shows types of atomsand how many of eachTo write an ionic compound’s formula, we need:1. the two types of ions(i.e., cations and anions)2. the charge on each ionNa+ and F–NaFBa2+ and O2–BaONa+ and O2–Na2OBa2+ and F–BaF2
5Notice that the pink pieces are cations (metals) and the blue are anions (non-metals) Br -BrKpotassium atombromine atompotassium ionpotassium bromidebromide ionKBrMg2+Br -K+O2-Br -K+1 Mg2+2 Br -potassium oxideMgBr2K2Omagnesium bromide
7criss-cross rule: charge on cation / anion “becomes” subscript of anion / cation** Warning:Reduce to lowest termsAl3+ and O2–Ba2+ and S2–In3+ and Br1–322231Al OBa SIn BrAl2O3BaSInBr3
8Writing Formulas w/Polyatomic Ions Parentheses are required only when you need morethan one “bunch” of a particular polyatomic ionBa2+ and SO42–BaSO4Mg2+ and NO2–Mg(NO2)2NH4+ and ClO3–NH4ClO3Sn4+ and SO42–Sn(SO4)2Fe3+ and Cr2O72–Fe2(Cr2O7)3NH4+ and N3–(NH4)3N
9Charges Reminder! Group 1: Group 2: Group 3: Group 5: Group 6: 1+2+3+3–2–1+1–2+3+3–2–1–
142. Use name of anion (it has the ending “ide”) 1+Na2+3+3–2–1–A. To name, giventhe formula:Ba1. Use name of cation2. Use name of anion (it has the ending “ide”)NaFsodium fluorideBaObarium oxideNa2Osodium oxideBaF2barium fluoride
151. Write symbols for the two types of ions Zn1+Ca2+3+3–2–1–AgB. To write formula,given the name:1. Write symbols for the two types of ions2. Balance charges to write formulasilver sulfideAg+S2–Ag2Szinc phosphideZn2+P3–Zn3P2calcium iodideCa2+I–CaI2
16Variable-Charge Cations with Elemental Anions i.e., “pulled off theTable” anionsThe variable-charge cations are:Pb, Sn, and the transition metals(but – of course! – not Ag or Zn)
17A. To name, given the formula: Cu Fe Figure out charge on cation. 2. Write name of cation.3. Write Roman numeralsin ( ) to show cation’s charge.Stock Systemof nomenclature4. Write name of anion.- 6FeOFe?iron oxideFe2+O2–iron (II) oxideFe2O3iron oxideFe?Fe3+Fe?Fe3+O2–O2–O2–iron (III) oxideCuBrcopper bromideCu+Cu?Br –copper (I) bromideCuBr2Cu?copper bromideCu2+Br –Br –copper (II) bromide
18Roman Numeral Review Greek Number Roman Numeral 1 I 2 II 3 III 4 IV 5 6VI7VII8VIII9IX10XNumberRoman Numeral1I5V10X50L100C
19B. To find the formula, given the name: 1. Write symbols for the two types of ions.2. Balance charges to write formula.CoSncobalt (III) chlorideCo3+Cl–CoCl3tin (IV) oxideSn4+O2–SnO2tin (II) oxideSn2+O2–SnO
20Traditional System of Nomenclature …used historically (and still some today) to namecompounds w/multiple-charge cationsTo use:1. Use Latin root of cation.2. Use -ic ending for higher charge;-ous ending for lower charge.3. Then say name of anion, as usual.
21Element Latin root -ic -ous gold, Au aur- Au3+ Au+ lead, Pb plumb- Pb4+ Pb2+tin, Sn stann- Sn4+ Sn2+copper, Cu cupr- Cu2+ Cu+iron, Fe ferr- Fe3+ Fe2+Write formulas:Write names:cuprous sulfidecuprous sulfidePb3P4Pb3P4Pb4+Pb?P3–plumbic phosphideCu+S2–Cu2Sauricauric nitridePb3P2Pb3P2Pb?Pb2+P3–plumbous phosphideAu3+N3-AuNferrous fluorideferrous fluorideSnSnCl4Sn4+Sn?Cl–stannic chlorideFe2+F–FeF2
22Compounds Containing Polyatomic Ions Insert name of ionwhere it should goin the compound’sname.Write formulas:iron (III) nitriteiron (III) nitriteFe3+NO2–Fe(NO2)3ammonium phosphideammonium phosphideNH4+P3–(NH4)3Pammonium chlorateammonium chlorateNH4+ClO3–NH4ClO3zinc phosphatezinc phosphateZn2+PO43–Zn3(PO4)2lead (II) permanganatelead (II) permanganatePb2+MnO4–Pb(MnO4)2
24C F Covalent Bonds (2 nonmetals) …atoms share e– to get a full valence shellC 1s2 2s2 2p2F 1s2 2s2 2p5Both need 8 valence e- for a full outer shell…otherwise known as the octet rule4 valence e-7 valence e-oxxCFxooxxoxx
25Draw the Lewis dot structure for the following elements: Si O P B Ar Br1s2 2s2 2p6 3s2 3p24 valence e-1s2 2s2 2p46 valence e-1s2 2s2 2p6 3s2 3p35 valence e-1s2 2s2 2p13 valence e-1s2 2s2 2p6 3s2 3p68 valence e-1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p57 valence e-
27Drawing Lewis Structures a model of a covalent molecule thatshows all of the valence e–1. Two shared e– make a single covalent bond,four make a double bond, etc.2. unshared pairs: pairs of unbonded valence e–3. Each atom needs a full outer shell, i.e., 8 e–.Exception: H needs 2 e–
28F2 Let’s bond two F atoms together… Each F has 7 v.e. and each needs 1 more e-FFFF2Now let’s bond C and F atoms together…carbon tetrafluoride (CF4)FCFFCFF
29Covalent Compounds -- contain two types of nonmetals nonmetals ** Key: FORGET CHARGES!What to do:Use Greek prefixes to indicate howmany atoms of each element, butdon’t use “mono” on first element.1 –2 –3 –4 –5 –6 –7 –8 –9 –10 –monohexadiheptatrioctatetranonapentadeca
31A Tale of Danger and Irresponsibility Dihydrogen Monoxide:A Tale of Danger and Irresponsibilitymajor component of acid rainfound in all cancer cellsinhalation can be deadlyexcessive ingestion results inacute physical symptoms:e.g., frequent urination,bloated sensation,profuse sweatingoften an industrial byproduct of chemicalreactions; dumped wholesale into rivers and lakes
32covalent compounds = molecular compounds -- have lower melting pointsthan do ionic compounds(consist of two or morenonmetal elements)butter
33Other Types of Bonds dipole-dipole forces hydrogen bonds DNAboiling H2Odipole-dipole forceshydrogen bondsLondon dispersion forcesion-dipole forcesThese are much weaker than ionic, covalent, or metallic bonds, but very important in determining states of matter, boiling and melting points, and molecular shape (among other things).
34Metallic Bonds In metals, valence shells of atoms overlap, so v.e– are free to travel between atoms through material.In insulators (like wood),the v.e– are attachedto particular atoms.Not so in metals.
35All due to free-moving v.e–. Properties of Metalsconduct heat and electricityductilemalleableAll due to free-moving v.e–.
36Empirical Formula and Molecular Formula lowest-termsformulashows the true numberand type of atoms in a m’culeCompoundMolecular FormulaEmpiricalFormulaglucoseC6H12O6propaneC3H8butaneC4H10naphthaleneC10H8sucroseC12H22O11octaneC8H18CH2OC3H8C2H5C5H4C12H22O11C4H9
38Formula Name? Metal + Nonmetal? Two Nonmetals? Ionic Multiple Single (Including NH4+)Two Nonmetals?IonicColumns 1, 2, 13 Ag+, Zn2+d,f-block Pb,SnMetal Type?MultipleSingleCovalentSteps 1 & 4 ONLYWrite name of cation (metal)Determine the charge on the metal by balancing the (-) charge from the anionWrite the charge of the metal in Roman Numerals and put in parenthesesWrite name of anion (Individual anions need –ide ending!)Use Prefixes!!!*Mono* Hexa Di Hepta Tri Octa Tetra Nona Penta DecaAdd –ide to 2nd element
39Name Formula? No Prefixes? Prefixes? Ionic Covalent Determine the ions present and the charge on each (Roman Numeral = cation charge, otherwise use PT)Balance formula (criss-cross)Reduce subscripts (if needed)FORGET CHARGES!!!Use prefixes to determine subscriptsDo NOT reduce subscripts!