Lewis Formulas PDF
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This document provides an explanation of Lewis formulas, including examples of ionic and molecular compounds like NaCl and CH4. It includes practice problems and diagrams, making it a helpful learning resource for chemistry.
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LEWIS FORMULAS Ionic Ionic bond Lewis Formulas Electronegativity difference ≥ 1.7 e- are transferred from metal to non- metal Attraction between cation & anion Lewis dot diagram Shows relative # valence e- Shows net (+) charge on cation and net (-) charge on...
LEWIS FORMULAS Ionic Ionic bond Lewis Formulas Electronegativity difference ≥ 1.7 e- are transferred from metal to non- metal Attraction between cation & anion Lewis dot diagram Shows relative # valence e- Shows net (+) charge on cation and net (-) charge on anion Charged species are enclosed in brackets NaCl Na Cl [Na] Cl + Practice: CaO MgCl 2 Al O 2 3 O Al O 2[Al] 3 O 3+ 2 - Al O Workbook Practice #3 Molecular Lewis Formulas Covalent bond Electronegativity difference < 1.7 Electrons are shared between atoms Lewis dot diagram Shows relative # valence e- Shared e-’s located between the atoms Cl2 O2 Why do many non-metals form diatomic molecules? H2 Cl Cl Cl Cl MORE STABLE! What about oxygen? O O O O Try N 2 N N N N Covalent bonds are classified as single (1 shared pair e-) double (2 shared pairs), or triple bonds (3 shared pairs) Atom # of # of Bonding Valence Bonding Capacity Electrons Electrons 4 single Carbon 4 4 4 bonds 2 sets of double Nitrogen 5 3 3 bonds Oxygen 6 2 2 2 single Halogens 7 1 1 bonds Hydrogen 1 1 1 1 double bond Drawing Lewis Formulas Draw the Lewis diagrams (if CH4 necessary) Sum up the valence e- for atoms involved C H H Determine the central atom H H Usually the atom that can form the most # of bonds 4+1+1+1+1 Arrange the atoms so that you form =8 a model of the structure H Each atom should have 8 e- surrounding it HC H Except H = 2 Ensure your total # valence e- is H Practice: NH3 SBr2 CO2 CH3OH Workbook Practice #4 Polyatomic Formulas NaOH Ionic compound Polyatomic ion = molecular Na+ OH - H O Na O Na H - [Na] O H + Workbook Practice #5 Workbook Practice #6 STRUCTURAL FORMULAS Ionic compounds Do not have structural formulas since their formulas are empirical Simplest whole number ratio of cations to anions Structural diagram of ionic compound Crystal lattice 3D solid of ionic compound Molecular compounds Replace bonding pairs with a line/stick (-) H H HC H H CH H H O O O O Practice: C2H4 C3H4 CH3COCH3 Chemical formula vs. Lewis diagram vs. Structural diagram CH4 Workbook Practice #7
