Presentation on theme: "Ionic Compounds Chapter 8. Remember…. Chemical bond Electron-dot structure Ionization energy Electron affinity – how much attraction an atom has for electrons."— Presentation transcript:
Ionic Compounds Chapter 8
Remember…. Chemical bond Electron-dot structure Ionization energy Electron affinity – how much attraction an atom has for electrons Electronegativity Octet rule Cation Anion
Atoms in contact will interact! Based on electronegativity difference: ionic (metals with nonmetals) polar covalent (varying degrees) nonpolar covalent (2 nonmetals) See page 169 What about metals with other metals?
Metallic atoms share their valence electrons freely in a sea of electrons to form alloys. Brass White gold 14K gold Steel Cast iron Bronze Pewter Cu + Zn Au + Ni or Pd Au + Cu or Ag Fe + C Fe + C + Si Cu + Sn Sn + Cu or Sb or Pb
Pause for penny demo!
Properties of other 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 Bond Electrostatic 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 anion Electrolyte – ionic compound whose aqueous solution conducts an electric current
Ionic Bond # electrons lost must = # electrons gained Calcium: 2+ charge Fluorine: 1- charge 1 Ca to every 2 F: CaF 2
Example Ionic Bond Sodium chloride Na +1, Cl -1 Methods: (p. 216) Electron configuration Orbital notation Electron-dot structures Atomic models
Energy 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 Bonds Lattice 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: Determined by ionic radius Smaller radii = higher lattice energy Determined by ionic charge Higher charge = higher lattice energy KI < KF < LiF < MgO
Predicting ionic ratios Based on charge ratios (formula units – simplest ratio of the ions) Cations first, anions second For example Na 1+ and Cl 1- ; therefore, will combine 1:1 NaClsodium chloride Na 1+ and S 2-; therefore, will combine 2:1 Na 2 Ssodium sulfide Be 2+ and N 3-; therefore, will combine 3:2 Be 3 N 2 beryllium nitride
Oxidation Number Charge of a monatomic ion (one-atom ion) Also known as oxidation state Group 1 : + 1 Group 2: +2
D-block cations Have varying oxidation numbers Charges 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 Compounds Name the cation (including charge if a d- block metal) and the anion with -ide Sodium chlorideGold (III) iodide Beryllium oxideZinc nitride
Polyatomic ions A group of atoms acting as one cation or anion Memorize the chart on page 224 (Table 8.6) Yes, all of ittest next Thursday If more than one needed – parenthesis Mg(ClO 3 ) 2 Oxyanions- negatively charged polyatomic ion containing oxygen
Make another A Vocabulary Memorize polyatomic ions Read about alloys Read about properties of ionic compounds Practice writing formulas and names
Covalent bonding …not til next chapter! ;0) The end!