Chemical Bonds I. Why Atoms Combine  Chemical Formula  Chemical Bond  Stability

H2OH2O 2 hydrogen atoms 1 oxygen atom A. Chemical Formula  Shows: 1) elements in the compound 2) ratio of their atoms

B. Chemical Bond  Strong attractive force between atoms or ions in a molecule or compound.  Formed by: transferring e - (losing or gaining) sharing e -

C. Stability  Octet Rule most atoms form bonds in order to have 8 valence e - full outer energy level like the Noble Gases! Ne  Stability is the driving force behind bond formation!

C. Stability  Transferring e -  Sharing e -

Chemical Bonds II. Kinds of Chemical Bonds  Ionic Bond  Covalent Bond  Comparison Chart

A. Ionic Bond  Attraction between 2 oppositely charged ions Ions - charged atoms formed by transferring e - from a metal to a nonmetal

A. Ionic Bond ions form a 3-D crystal lattice NaCl

B. Covalent Bond  Attraction between neutral atoms formed by sharing e - between two nonmetals

B. Covalent Bond covalent bonds result in discrete molecules Cl 2 H2OH2O NH 3

Covalent Bond –sharing

 Nonpolar Covalent Bond e - are shared equally usually identical atoms B. Covalent Bond

 Polar Covalent Bond e - are shared unequally between 2 different atoms results in partial opposite charges ++ -- B. Covalent Bond

 Nonpolar  Polar  Ionic View Bonding Animations.Bonding Animations B. Covalent Bond

C. Comparison Chart IONIC COVALENT Electrons Melting Point Soluble in Water Conduct Electricity Other Properties transferred from metal to nonmetal high yes (solution or liquid) yes crystal lattice of ions, crystalline solids shared between nonmetals low no usually not molecules, odorous liquids & gases

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Chemical Bonds III. Naming Molecular Compounds  Molecular Names  Molecular Formulas

 Write the names of both elements.  Change the final ending to -ide.  Add prefixes to indicate subscripts.  Only use mono- prefix with oxide. A. Molecular Names

PREFIX mono- di- tri- tetra- penta- hexa- SUBSCRIPT A. Molecular Names

 CCl 4  N 2 O  SF 6 carbon tetrachloride dinitrogen monoxide sulfur hexafluoride A. Molecular Names

 Write the more metallic element first.  Add subscripts according to prefixes. B. Molecular Formulas

 phosphorus trichloride  dinitrogen pentoxide  dihydrogen monoxide PCl 3 N 2 O 5 H 2 O B. Molecular Formulas

 The Seven Diatomic Elements Br 2 I 2 N 2 Cl 2 H 2 O 2 F 2 B. Molecular Formulas

Chemical Bonds IV. Naming Ionic Compounds  Oxidation Number  Ionic Names  Ionic Formulas

A. Oxidation Number  The charge on an ion.  Indicates the # of e - gained/lost to become stable

 Write the names of both elements, cation first.  Change the anion’s ending to -ide.  Write the names of polyatomic ions.  For ions with variable oxidation #’s, write the ox. # in parentheses using Roman numerals. Overall charge = 0. (Transition metals) B. Ionic Names

 NaBr  Na 2 CO 3  FeCl 3 sodium bromide sodium carbonate iron(III) chloride B. Ionic Names

 Write each ion. Put the cation first.  Overall charge must equal zero. If charges cancel, just write the symbols. If not, crisscross the charges to find subscripts.  Use parentheses when more than one polyatomic ion is needed.  Roman numerals indicate the oxidation #. C. Ionic Formulas

 potassium chloride  magnesium nitrate  copper(II) chloride K + Cl   KCl Mg 2+ NO 3   Mg(NO 3 ) 2 Cu 2+ Cl   CuCl 2 C. Ionic Formulas

 calcium oxide  aluminum chlorate  iron(III) oxide Ca 2+ O 2   CaO Al 3+ ClO 3   Al(ClO 3 ) 3 Fe 3+ O 2   Fe 2 O 3 C. Ionic Formulas

Covalent Bond Naming  SiO 2 silicon dioxide  NO nitrogen monoxide  XeF 4 Xenon tetrafluoride

Covalent Bond Naming P4S3P4S3 Tetraphosphorus trisulfide  PBr 3 phosphorus tribromide  CS 2 carbon disulfide

Covalent bond formula  Nitrogen trifluoride NF 3 Dinitrogen pentoxide N2O5N2O5

Covalent Bond formula  Trisilicon tetranitride Si 3 N 4  Carbon dioxide CO 2