Chemical Bonds

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Chemical Bonds

• I. Why Atoms Combine
• Chemical Formula
• Chemical Bond
• Stability

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A. Chemical Formula

• Shows
• 1) elements in the compound
• 2) ratio of their atoms

H2O
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B. Chemical Bond

• Strong attractive force between atoms or ions in
  a molecule or compound.
• Formed by
• transferring e- (losing or gaining)
• sharing e-

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C. Stability

• Octet Rule
• most atoms form bonds in order to have 8 valence
  e-
• full outer energy level
• like the Noble Gases!

• Stability is the driving force behind bond
  formation!

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C. Stability

• Transferring e-

• Sharing e-

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Chemical Bonds

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

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A. Ionic Bond

• Attraction between 2 oppositely charged ions
• Ions - charged atoms
• formed by transferring e-from a metal to a
  nonmetal

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A. Ionic Bond

• ions form a 3-D crystal lattice

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B. Covalent Bond

• Attraction between neutral atoms
• formed by sharing e- between two nonmetals

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B. Covalent Bond

• covalent bonds result in discrete molecules

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Covalent Bond sharing
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B. Covalent Bond

• Nonpolar Covalent Bond

• e- are shared equally
• usually identical atoms

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B. Covalent Bond

• Polar Covalent Bond

• e- are shared unequally between 2 different atoms
• results in partial opposite charges

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B. Covalent Bond

• Nonpolar
• Polar
• Ionic

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

• III. Naming Molecular Compounds
• Molecular Names
• Molecular Formulas

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A. Molecular Names

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

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A. Molecular Names

• PREFIX
• mono-
• di-
• tri-
• tetra-
• penta-
• hexa-

• SUBSCRIPT
• 1
• 2
• 3
• 4
• 5
• 6

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A. Molecular Names

• CCl4
• N2O
• SF6

• carbon tetrachloride

• dinitrogen monoxide

• sulfur hexafluoride

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B. Molecular Formulas

• Write the more metallic element first.

• Add subscripts according to prefixes.

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B. Molecular Formulas

• phosphorus trichloride
• dinitrogen pentoxide
• dihydrogen monoxide

• PCl3

• N2O5

• H2O

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B. Molecular Formulas

• The Seven Diatomic Elements

Br2 I2 N2 Cl2 H2 O2 F2
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Chemical Bonds

• IV. Naming Ionic Compounds
• Oxidation Number
• Ionic Names
• Ionic Formulas

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A. Oxidation Number

• The charge on an ion.
• Indicates the of e- gained/lost to become
  stable.

1
0
2
3
4
3-
2-
1-
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B. Ionic Names

• Write the names of both elements, cation first.
• Change the anions 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)

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B. Ionic Names

• NaBr
• Na2CO3
• FeCl3

• sodium bromide

• sodium carbonate

• iron(III) chloride

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C. Ionic Formulas

• 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 .

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C. Ionic Formulas

• potassium chloride
• magnesium nitrate
• copper(II) chloride

• K Cl- ? KCl

• Mg2 NO3- ? Mg(NO3)2

• Cu2 Cl- ? CuCl2

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C. Ionic Formulas

• calcium oxide
• aluminum chlorate
• iron(III) oxide

• Ca2 O2- ? CaO

• Al3 ClO3- ? Al(ClO3)3

• Fe3 O2- ? Fe2O3

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Covalent Bond Naming

• SiO2
• silicon dioxide
• NO
• nitrogen monoxide
• XeF4
• Xenon tetrafluoride

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Covalent Bond Naming

• P4S3
• Tetraphosphorus trisulfide
• PBr3
• phosphorus tribromide
• CS2
• carbon disulfide

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Covalent bond formula

• Nitrogen trifluoride
• NF3
• Dinitrogen pentoxide
• N2O5

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Covalent Bond formula

• Trisilicon tetranitride
• Si3N4
• Carbon dioxide
• CO2