Ionic CompoundsIonic CompoundsChapter 8
Remember….Remember….Chemical bondElectron-dot structureIonization energyElectron affinity – how much
attraction an atom has for electrons
ElectronegativityOctet ruleCation Anion
Atoms in contact will Atoms in contact will interact!interact!Based on electronegativity
difference:◦1.8-3.3 ionic (metals with nonmetals)◦0.4-1.7 polar covalent (varying
degrees)◦0.0-0.3 nonpolar covalent (2
nonmetals)◦ See page 169
What about metals with other metals?
Metallic atoms share their valence Metallic atoms share their valence electrons freely in a “sea of electrons” electrons freely in a “sea of electrons” to form to form alloysalloys..
BrassWhite gold14K goldSteelCast ironBronzePewter
Cu + ZnAu + Ni or PdAu + Cu or AgFe + CFe + C + SiCu + SnSn + Cu or Sb or
Pb
Pause for penny demo!Pause for penny demo!
http://www.slossfurnaces.com/
Properties of other Properties of other bonding:bonding: Ionic
◦ Crystalline arrangement (brittle/will shatter)
◦ High melting and boiling temperatures
◦ Ratio of atoms involved is determined by charges
◦ Non-conductive unless molten, dissolved in water
Covalent◦ Molecular
arrangement◦ Lower melting and
boiling temperatures (may even be gases!)
◦ Ratio of atoms involved is determined experimentally
◦ Generally non-conductive
Ionic BondIonic BondElectrostatic force that holds
oppositely charged particles together in an ionic compound
Binary ionic compounds – contain only two different elements◦A metallic cation and a nonmetallic
anionElectrolyte – ionic compound
whose aqueous solution conducts an electric current
Ionic BondIonic Bond# electrons lost must = #
electrons gained◦Calcium: 2+ charge◦Fluorine: 1- charge◦1 Ca to every 2 F: CaF2
Example Ionic BondExample Ionic BondSodium chlorideNa+1 , Cl-1 Methods: (p. 216)
◦Electron configuration◦Orbital notation◦Electron-dot structures◦Atomic models
Energy and Ionic BondsEnergy and Ionic Bonds
Endothermic – energy absorbed during a chemical reaction
Exothermic – energy released during a chemical reaction◦Ionic compounds always exothermic
reaction
Energy and Ionic BondsEnergy and Ionic BondsLattice energy – energy required
to separate one mole of ions of an ionic compound◦Reflects strength of forces holding
ions together ◦More negative lattice energy,
stronger force of attraction
Crystal strength:Crystal strength:Determined by ionic radius
◦Smaller radii = higher lattice energy
Determined by ionic charge◦Higher charge = higher lattice
energy
KI < KF < LiF < MgO
Predicting ionic ratiosPredicting ionic ratiosBased on charge ratios (“formula
units” – simplest ratio of the ions)Cations first, anions secondFor example
◦Na 1+ and Cl 1- ; therefore, will combine 1:1 NaCl “sodium chloride”
◦Na 1+ and S 2-; therefore, will combine 2:1 Na2S “sodium sulfide”
◦Be 2+ and N 3-; therefore, will combine 3:2 Be3N2 “beryllium nitride”
Oxidation NumberOxidation NumberCharge of a monatomic ion (one-
atom ion)Also known as oxidation stateGroup 1: +1Group 2: +2
D-block cationsD-block cationsHave varying oxidation numbersCharges of these elements are
indicated with Roman numerals (Stock method) ◦Cu (I) or Cu (II)
OR name changes (less common)◦“-ic” means higher option (cupric =
2+)◦“-ous” means lower option (cuprous
= 1+)
Naming Binary Ionic Naming Binary Ionic CompoundsCompoundsName the cation (including
charge if a d-block metal) and the anion with “-ide”
Sodium chloride Gold (III) iodideBeryllium oxide Zinc nitride
Polyatomic ionsPolyatomic ionsA group of atoms acting as one
cation or anion◦Memorize the chart on page 224 (Table
8.6)◦Yes, all of it—test next Thursday
If more than one needed – parenthesis◦Mg(ClO3)2
Oxyanions- negatively charged polyatomic ion containing oxygen
Make another ‘A’Make another ‘A’VocabularyMemorize polyatomic ionsRead about alloysRead about properties of ionic
compoundsPractice writing formulas and
names
Covalent bondingCovalent bonding…not ‘til next chapter! ;0)
The end!
Top Related