Chemical Bonding

Chemical BondingWhy atoms bond together?To be HAPPY ATOMS! The idea behind Happy Atoms is that atomic shells like to be full.Chemical BondAn attractive force that makes almost every atom to be attached to other atoms

An element will either lose, gain or share electrons in their outermost shellTypes of BondsIonic Bond- involve the attraction between the positively charged and negatively charged ions- formed between metals and nonmetals- hold ions together in an ionic compoundTypes of BondsCovalent Bond- generally involves sharing pairs of electrons between nonmetals- it holds atoms together in a covalent compoundTypes of BondsMetallic Bond- the existing force of attraction between the metal positive ions and the highly mobile electrons in the metals

Ionic CompoundShow the formation of an ionic compound NaCl (sodium chloride).

ExerciseElementsFormationCationAnionChemical FormulaNa and OMg and ClAl and SCovalent Bondis the chemical bond that involves the sharing of pairs of electrons between atoms.

COVALENT COMPOUNDS- Compounds that contain only covalent bonds.Covalent Bond F2 molecule

Covalent BondLEWIS STRUCTURE/ LEWIS ELECTRON-DOT SYMBOLS (LEDS)- Is a representation of covalent bonding in which shared electron pairs are shown either as lines or as pairs of dots between two atoms, and lone pairs are shown as pairs of dots on individual atoms.ExerciseElementsFormationLewis StructureChemical Formula1) O and 2Cl2) N and 3F3) C and 4F4) 2O 5) 2NIonic BondCovalent BondTransfer of electron/sSharing of electronsMetal to nonmetal elementsBetween nonmetal elementsAttraction between charge of ionsAttraction between positive nucleus and shared electronsDetermine if ionic or covalent compound.NaClSF6KFNa2OBaOCH4SO2PCl5CS2N2O5Properties of Ionic and Covalent CompoundsIonic Compounds

Crystalline solids (made of ions)

High melting and boiling points

Conduct electricity when melted

Many soluble in water but not in nonpolar liquidCovalent Compounds

Gases, liquids, or solids (made of molecules)

Low melting and boiling points

Poor electrical conductors in all phases

Many soluble in nonpolar liquids but not in waterWriting and Naming CompoundsIonic CompoundsConsist of cations (positive ions) and anions (negative ions) held together by electrostatic attractionUsually metal + nonmetal(s)Made of monatomic ions, polyatomic ions, and/or bothMonatomic ions: consist of a single atomPolyatomic ions: consist of more than one atomNaming monatomic cationsMetal atom lose valence electrons to form positively charged ions, called cations.

I. Groups IA, IIA, IIIA elements silver (Ag) and zinc (Zn) form only one type of ion. element name + ion

e.g. Na+ = sodium ionSr2+ = strontium ionZn2+ = zinc ion18II. The Stock System is used to name transition metals and other metals that form more than one ion:- iron (Fe) forms two ions: Fe2+ and Fe3+- lead (Pb) forms two ions: Pb2+ and Pb4+

element name (charge in Roman Numerals) + ione.g. Fe2+ = iron (II) ionFe3+ = iron (III) ion

Name the cationsLi+Ag+Al3+Mn2+Fe3+K+Ca2+Ba2+Cu2+Mg2+Sn4+Co3+Na+Ti4+Ni2+Naming monatomic anionsNonmetal atoms gain valence electrons to form negatively charged ions called anions.

element name root word + -ide + ion

e.g. O2- = oxide ionN3- = nitride ionName the anions.F-Br-I-Cl-S2-P3-

Naming Polyatomic IonsPolyatomic ions ions made up of more than one atom

Bicarbonate ionHCO3-1Nitrite ionNO2-2Nitrate ionNO3-3Hydroxide ionOH-4Cyanide ionCN-5Permanganate ionMnO4-6Hypochlorite ionClO-7Chlorite ionClO2-8Chlorate ionClO3-9Perchlorate ionClO4-10Ammonium ionNH4+11Hydronium ionH3O+12Name the following polyatomic ions.CN-SO42-OH-NH4+CrO42-NO3-PO43-C2H3O2-H3O+MnO4-

Writing Chemical Formulas Given Individual IonsK+ + OH-Na+ +S2-Ba2++ N3-Ti4+ + O2-Cu+ + O2-Sr2+ + CO32-Ca2+ + NO3-Pb4+ + CO32-Ni2+ + PO43-Li+ + CO32-Chemical Formulas and Names from Individual IonsCompounds are named from the individual ions they come from.Chemical Formulas and Names from Individual IonsName the cation and the anion, then remove ion from each name:1. Na+ = sodium ionCl- = chloride ion => NaCl = sodium chloride

2. K+ = potassium ionCO32- = carbonate ion => K2CO3 = potassium carbonate3. Fe3+= iron (III) ionNO3- = nitrate ion => Fe(NO3)3 = iron (III) nitrateWriting chemical formulas given the compound name.Get the individual ions from the name, then combine them using the criss-cross method.e.g.barium chloride => barium = Ba2+ chloride=Cl-Ba2+ Cl- => BaCl2

Aluminum sulfate=> aluminum = Al3+ sulfate=SO42-Al3+ SO42- => Al2(SO4)3Naming Molecular CompoundsIndicate number of atoms of each element with Greek prefix before element name.# of atomsGreek Prefix# of atomsGreek Prefix1mono(usually omitted)6hexa2di7hepta3tri8octa4tetra9nona5penta10decaNaming Molecular CompoundsIndicate number of atoms of each element with Greek prefix before element name.For the 1st element: Greek prefix + element nameFor the 2nd element:Greek prefix + element name rootword + -ide

Note: Mono is generally omitted, except in common names like CO = carbon monoxide

Determining formulas of Molecular CompoundsUse Greek prefix(es) to determine number of atoms of each element in formula.

Silicon tetrachlorideSiCl4Arsenic pentafluorideAsF5Silicon disulfideSiS2Boron trifluorideBF3Carbon monoxideCOCarbon dioxideCO2Carbon tetrafluorideCF4Chlorine dioxideClO2Nitrogen monoxideNOOxygen difluorideOF2Dinitrogen trioxideN2O3Selenium hexafluorideSeF6Selenium hexachlorideSeCl6Carbon tetrabromideCBr4Phosphorus pentachloridePCl5Diboron tetrachlorideB2Cl4Phosphorus tribromidePBr3Sulfur hexafluorideSF6Tetraphosphorus trisulfideP4S3Sulfur trioxideSO3Dinitrogen monoxideN2ODiphosphorus pentoxideP2O5Dichlorine heptoxideCl2O7Carbon tetrachlorideCCl4Dinitrogen pentoxideN2O5Molecular GeometryMolecular GeometryIs the three-dimensional arrangement of atoms in a molecule.Valence-Shell Electron-Pair Repulsion (VSEPR) model -it accounts for the geometric arrangements of electron pairs around a central atom in terms of the electrostatic repulsion between electron pairsAX2

AX3

AX4

AX5

AX6

ElectronegativityThe ability of an atom to attract toward itself the electrons in a chemical bondH-F

Polar Covalent BondIn this type of covalent bond, the electrons spend more time in the vicinity of one atom than the other.Unequal distribution of electrons

H-H

Nonpolar Covalent BondIn this type of covalent bond, the electrons spend the same amount of time in the vicinity of each atom.Equal sharing of electrons

Bond Type using Electronegativity DifferenceBond TypeElectronegativity DifferenceNonpolar Covalent Bond0 less than 0.4Polar Covalent Bond0.4 1.78Ionic BondGreater than 1.78Indicate the type of bond. Rank the following bonds in the order of increasing polarityNa-FFr-BrC-NSe-SBr-O4.0 0.9 = 3.1ionic bond2.8 0.7 = 2.1 ionic bond3.0 2.5 = 0.5 polar covalent bond2.5 2.4 = 0.1 nonpolar covalent bond3.5 2.8 = 0.7 polar covalent bondSe-S < C-N < Br-O < Fr-Br < Na-FDipole Moment ()A quantitative measure of the polarity of a bond

The product of the charge Q and the distance r between the charges = Q X r

Expressed in debye units (D), named for Peter Debye

Polar Molecule vs Nonpolar MoleculePolar Molecule

Nonpolar Molecule

Predict whether each of the following molecules has a dipole moment:BrClBF3 (trigonal planar)CH2Cl2 (tetrahedral)Why?

Intramolecular ForceBonding forcesRelatively strong involve larger charges that are close togetherIntermolecular ForceRelatively weak involve smaller charges that are farther apart.Comparison of Bonding and Nonbonding Forces

Comparison of Bonding and Nonbonding Forces

Ion-Dipole Forces

Dipole-Dipole forces

Hydrogen Bond

Ion Induced Dipole Forces

Dipole Induced Dipole Forces

Dispersion (London) Forces

For each pair, identify the key intermolecular force(s) in each substance.MgCl2 and PCl3CH3NH2 and CH3FCH3OH and CH3CH2OHHexane (CH3 CH2 CH2 CH2 CH2 CH3) and 2,2-Dimethylbutane CH3

CH3 C CH2CH3

CH3