Drill Quiz: Define the law of conservation of mass. Determine the limited reactant in the following: 4Al + 3O2 2Al2O3 10g of Al and 10g of Oxygen gas were used to produce Al2O3.

Objective: SWBAT: Distinguish between cations and anions in order to model ionic bonding by combining Lewis Dot diagrams.

SAT Enrichment: C3H8 + 5O2 3CO2 + 4H2O If the number of moles of O2 is given in a problem, and the number of CO2 is desired, the appropriate mole ratio to use is…. 1 mole C3H8 / 3 moles CO2 3 moles CO2 / 5 moles O2 4 moles H2O / 5 moles O2 5 moles O2 / 3 moles CO2 5 moles O2 / 4 moles H2O

Webquest 30 min Complete the WebQuest using the computers. http://www.visionlearning.com/library/module_viewer.php?mid=55&mcid=&l= 30 min

Chemical Bonding Chemical bonding: the connection of two or more atoms based on the attraction between positive nuclei and negative electrons

Why bond? To have a full valence shell (like the nobel gases) of electrons What constitutes a full valence shell? Octet (8) rule Exceptions Hydrogen: 2 electrons total Beryllium: 4 electrons total Boron: 6 electrons total

Important Terms Ionic bonding: the formation of chemical bonds between ions that have gained or lost electrons to achieve a full valence shell Ionic bonds typically form between a metal and a nonmetal

More Important Terms Ion: an atom that has become charged by gaining or losing electrons Cation (kat-eye-on): a positive ion Cations have lost electrons Anion (an-eye-on): a negative ion Anions have gained electrons Polyatomic Ion: an ion including more than one atom Polyatomic ions can replace either a metal or a nonmetal in an ionic compound

How do ionic bonds form? Metals and nonmetals are ionized Electrons are transferred from the metals to the nonmetals The metals become positive (cations) The nonmetals become negative (anions) The ionic bond is formed by the attraction of the positive cation to the negative anion

Ionic Bonding Na + → → Cl Na+ + Cl- NaCl Example: Sodium plus chlorine • • • • Na + • • → • • → • Cl Na+ + Cl- NaCl • • • • • • •

How can you predict what an ion’s charge will be? The representative groups on the Periodic Table can show how many electrons elements will gain or lose 1+ 2+ 3+ 4± 3- 2- 1- 1 H Hydrogen 3 Li Lithium 11 Na Sodium 19 K Potassium 37 Rb Rubidium 55 Cs Cesium 87 Fr Francium 4 Be Beryllium 12 Mg Magnesium 20 Ca Calcium 38 Sr Strontium 56 Ba Barium 88 Ra Radium 5 B Boron 13 Al Aluminum 31 Ga Gallium 49 In Indium 81 Tl Thallium 6 C Carbon 14 Si Silicon 32 Ge Germanium 50 Sn Tin 82 Pb Lead 7 N Nitrogen 15 P Phosphorus 33 As Arsenic 51 Sb Antimony 83 Bi Bismuth 8 O Oxygen 16 S Sulfur 34 Se Selenium 52 Te Tellurium 84 Po Polonium 9 F Fluorine 17 Cl Chlorine 35 Br Bromine 53 I Iodine 85 At Astatine 2 He Helium 10 Ne Neon 18 Ar Argon 36 Kr Krypton 54 Xe Xenon 86 Rn Radon Group 2: Alkaline Earth Metals Lose 2 Electrons Charge: 2+ Group 4 Gain or lose 4 Electrons Charge: 4± Group 1: Alkali Metals Lose 1 Electron Charge: 1+ Group 8: Noble Gases Full Valence Shell Charge: 0 Group 7: Halogens Gain 1 Electrons Charge: 1- Group 6: Chalcogens Gain 2 Electrons Charge: 2- Group 5 Gain 3 Electrons Charge: 3- Group 3 Lose 3 Electrons Charge: 3+

Properties of Ionic Compounds Strong bond Dissociation Large electronegativity difference

Electronegativities Electronegativities for the first six periods The difference between two elements’ electronegativities indicates the degree of electron sharing (or transfer) in a chemical bond As electronegativity difference increases, degree of sharing decreases H 2.1   Li 1.0 Be 1.5 B 2.0 C 2.5 N 3.0 O 3.5 F 4.0 Na 0.9 Mg 1.2 Al Si 1.8 P S Cl K 0.8 Ca Sc 1.3 Ti V 1.6 Cr Mn Fe Co 1.9 Ni Cu Zn Ga Ge As Se 2.4 Br 2.8 Rb Sr Y Zr 1.4 Nb Mo Tc Ru 2.2 Rh Pd Ag Cd 1.7 In Sn Sb Te I Cs 0.7 Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At

Predicting Bond Type An electronegativity difference of ≥ 1.7 results in an ionic bond Example: KBr EN of K = 0.8 EN of Br = 2.8 2.8 – 0.8 = 2.0 2.0 is greater than or equal to 1.7, so the bond is ionic.

Example MgO Mg: 1.2 O: 3.5 3.5 – 1.2 = 2.3 Ionic

Example H2O H: 2.1 O: 3.5 3.5-2.1=1.4 Not ionic

Extension: Thermite Reaction Video: http://jchemed.chem.wisc.edu/JCESoft/CCA/samples/cca7thermite.html 10 min

Summary Did we accomplish the objective? Explain. Identify the difference b/w cations and anions. What criteria would you use to assess the bonding of a compound? Construct a method you can use to determine the formation of a compound using Lewis dot diagrams.

Exit Ticket/Homework Ionic Bonding Exit ticket: Homework NONE! 5 min