Chemical Bonding I. Introduction to Bonding I II III IV A. Vocabulary Chemical Bond attractive force between atoms or ions that binds them together as a unit bonds form in order to… decrease potential energy (PE) increase stability A. Vocabulary CHEMICAL FORMULA IONIC COVALENT Formula Unit Molecular Formula NaCl CO2 A. Vocabulary COMPOUND 2 elements Binary Compound NaCl more than 2 elements Ternary Compound NaNO3 A. Vocabulary ION 1 atom 2 or more atoms Monatomic Ion Polyatomic Ion + Na NO3 - B. Types of Bonds IONIC COVALENT Bond Formation e- are transferred from metal to nonmetal e- are shared between two nonmetals Type of Structure crystal lattice true molecules Physical State solid liquid or gas Melting Point high low Solubility in Water yes usually not Electrical Conductivity yes (solution or liquid) no Other Properties odorous B. Types of Bonds METALLIC Bond Formation e- are delocalized among metal atoms Type of Structure “electron sea” Physical State solid Melting Point very high Solubility in Water no Electrical Conductivity yes (any form) Other Properties malleable, ductile, lustrous C. Bond Polarity Most bonds are a blend of ionic and covalent characteristics. Difference in electronegativity determines bond type. C. Bond Polarity Electronegativity Attraction an atom has for a shared pair of electrons. higher e-neg atom lower e-neg atom + C. Bond Polarity Electronegativity Trend (p. 151) Increases up and to the right. C. Bond Polarity Nonpolar Covalent Bond e- are shared equally symmetrical e- density usually identical atoms C. Bond Polarity Polar Covalent Bond e- are shared unequally asymmetrical e- density results in partial charges (dipole) + C. Bond Polarity Nonpolar Polar Ionic View Bonding Animations. C. Bond Polarity Examples: Cl2 3.0-3.0=0.0 Nonpolar HCl 3.0-2.1=0.9 Polar NaCl 3.0-0.9=2.1 Ionic Chemical Bonding II. Ionic Compounds I II III IV A. Energy of Bond Formation Lattice Energy Energy released when one mole of an ionic crystalline compound is formed from gaseous ions B. Lewis Structures Covalent – show sharing of eIonic – show transfer of e- B. Lewis Structures Covalent – show sharing of eIonic – show transfer of e- C. Ionic Nomenclature Ionic Formulas Write each ion, cation first. Don’t show charges in the final formula. Overall charge must equal zero. If charges cancel, just write symbols. If not, use subscripts to balance charges. Use parentheses to show more than one polyatomic ion. Stock System - Roman numerals indicate C. Ionic Nomenclature Ionic Names Write the names of both ions, cation first. Change ending of monatomic ions to -ide. Polyatomic ions have special names. Stock System - Use Roman numerals to show the ion’s charge if more than one is possible. Overall charge must equal zero. C. Ionic Nomenclature Consider the following: Does it contain a polyatomic ion? -ide, 2 elements no -ate, -ite, 3+ elements yes Does it contain a Roman numeral? Check the table for metals not in Groups 1 or 2. No prefixes! C. Ionic Nomenclature Common Ion Charges 1+ 0 2+ 3+ NA 3- 2- 1- C. Ionic Nomenclature potassium chloride K+ Cl- KCl magnesium nitrate Mg2+ NO3- Mg(NO3)2 copper(II) chloride Cu2+ Cl- CuCl2 C. Ionic Nomenclature NaBr sodium bromide Na2CO3 sodium carbonate FeCl3 iron(III) chloride Chemical Bonding III. Molecular Compounds I II III IV A. Energy of Bond Formation Potential Energy based on position of an object low PE = high stability A. Energy of Bond Formation Potential Energy Diagram attraction vs. repulsion no interaction increased attraction A. Energy of Bond Formation Potential Energy Diagram attraction vs. repulsion increased repulsion balanced attraction & repulsion A. Energy of Bond Formation Bond Energy Energy required to break a bond Bond Energy Bond Length A. Energy of Bond Formation Bond Energy Short bond = high bond energy B. Lewis Structures Electron Dot Diagrams show valence e- as dots distribute dots like arrows in an orbital diagram 4 sides = 1 s-orbital, 3 p-orbitals EX: oxygen 2s 2p O X B. Lewis Structures Octet Rule Most atoms form bonds in order to obtain 8 valence eFull energy level stability ~ Noble Gases Ne B. Lewis Structures Nonpolar Covalent - no charges Polar Covalent - partial charges + + C. Molecular Nomenclature Prefix System (binary compounds) 1. Less e-neg atom comes first. 2. Add prefixes to indicate # of atoms. Omit mono- prefix on first element. 3. Change the ending of the second element to -ide. C. Molecular Nomenclature PREFIX monoditritetrapentahexaheptaoctanonadeca- NUMBER 1 2 3 4 5 6 7 8 9 10 C. Molecular Nomenclature CCl4 carbon tetrachloride N2O dinitrogen monoxide SF6 sulfur hexafluoride C. Molecular Nomenclature arsenic trichloride AsCl3 dinitrogen pentoxide N2O5 tetraphosphorus decoxide P4O10 C. Molecular Nomenclature The Seven Diatomic Elements Br2 I2 N2 Cl2 H2 O2 F2 H N O F Cl Br I