Ch. 12 Notes---Covalent Bonds

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Ch. 12 Notes---Covalent Bonds

• Covalent Bonds
• ____________ electrons between two atoms in
  order to fill the outer energy level (or shell)
• Each bond involves the sharing of _____
  _________ of electrons.
• Single Bonds __ e-s Double Bonds __ e-s
  Triple Bonds__ e-s

Sharing
one pair
2
4
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Sharing
Sharing is Caring!! Caring is Covalent!!!
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Polar and Nonpolar Bonds

• Even though the electrons in a covalent bond are
  shared, sometimes the attraction for the bonded
  pair, (the _____________________), is uneven.
  This gives rise to 3 bond types.
• nonpolar covalent bonds ____________ sharing
  of the e- pair
• polar covalent bonds ________________ sharing
  of the e- pair
• ionic bonds a ___________ of e-s from the
  metal to the nonmetal
• How To Determine the Bond Type
• Bond type is based on the electronegativity
  _____________ between the two bonded atoms.

electronegativity
equal
unequal
transfer
difference
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Figure 12.4 The three possible types of bonds.
nonpolar
polar
ionic
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Figure 12.4 Electronegativity values for
selected elements.
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• How To Determine the Bond Type
• 0 to 0.4 ______________ covalent bond
• 0.5 to 2.0 _____________ covalent bond
• Above 2.0 _______________ bond
• Practice Problems Determine the type of bond
  that forms between the atoms in the following
  compounds.
• a) CO2 b) NaCl c) CH4

nonpolar
polar
ionic
2.5 3.5
0.9 3.0
2.5 2.1
1.0 polar covalent
2.1 ionic
0.4 nonpolar covalent
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• Ways to Represent Covalent Bonds in Compounds
• Quantum Mechanical or Bohr Model of the Atom.

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• Ways to Represent Covalent Bonds in Compounds
• Quantum Mechanical or Bohr Model of the Atom.

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• Ways to Represent Covalent Bonds in Compounds
• (3) Dots for bonds. (Lewis Structures)
• a) H2 H H ?
• b) F2 F F ?
• c) N2 N N ?
  (triple bond)
• d) NH3

HH
..
..
..
..
FF
..
..
..
..




NN


..
HNH
..
H
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• Ways to Represent Covalent Bonds in Compounds
• (4) Lines for bonds.
• a) H2
• b) F2
• c) N2
• d) NH3
• e) H2O

HH
..
..
FF
..
..
NN

HNH
?
H
..
HO
?
H
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• Coordinate Covalent Bonds
• Both of the electrons that make the bond come
  from the ________ _______________ .
• Example CO (carbon monoxide)

same
element
?
C ___ ___ ___ ___
2s 2p
?
?
?
?
?
O ___ ___ ___ ___
2s 2p
?
?
?
?
..
C O
..
..
Two of the bonds are normal, and the third bond
is a coordinate covalent bond.

C O

?
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The 7 Diatomic Elements

• Some elements will covalently bond to themselves
  to form a molecule composed of ____ atoms.
• These elements are never found in nature as
  single atoms. Instead, they will be bonded as a
  ________ when they are in the _________________
  state.
• The 7 diatomic elements are the gases H, O, N,
  and all of the _________________, (Group 7A).
• H2, O2, N2, Cl2, Br2, I2, F2
• HONClBrIF

two
pair
elemental
halogens
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Air contains N2 and O2 molecules.
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The decomposition of two water molecules
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• Octet Rule
• Atoms want ___ e-s in their outer shell when
  forming compounds.
• This will mean ___ dots around them all
  together. This is the stable e- configuration of
  a __________ _______!
• Important exception Hydrogen only needs __ to
  be full (like He).
• Other Exceptions
• PCl5 (___ e-) SF6 (___ e-)
  BF3(___e-)

8
8
noble gas
2
10
12
6
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Resonance

• Resonance is the ability to draw 2 or more
  different e- dot notations that obey the octet
  rule.
• Examples O3 (ozone) and SO2

Practice Problem Draw the resonance structures
for CO3-2.
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Properties of Ionic Compounds and Covalent
Molecules

• Molecular
• ________________ of electricity
• formed between two _______________
• usually have ________ melting points
• solubility in water _______ (polar dissolve
  nonpolar insoluble)
• forms ______________________solids.
• For a compound to to conduct electricity it must
  have
• (1) Charged Particles (________)
• (2) Particles Free to Move (___________ or
  __________ phase)

Insulators
nonmetals
low
varies
covalent crystalline
ions
liquid
aqueous
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Quartz

• Quartz is the common mineral form of silicon
  dioxide (SiO2). It is the dominant mineral in
  most sands and sandstones.

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• Molecular Compounds (____________)
• Name or formula starts with a ____________
  (exception NH4 )
• Other quick ways to tell if the compound is
  molecular
• Name has prefixes and also ends in -ide. (It
  must have both!)
• Examples _________________,____________________
  ___

molecules
nonmetal
carbon dioxide
dinitrogen pentoxide
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• Naming Molecular Compounds
• You do not use the ion sheet for molecules
  because no __________ are needed. They
  ______________ electrons instead of transferring
  them.
• Use ________________ to indicate the and kind
  of atom in the compound.
• mono1 di2 tri3 tetra4 penta5
  hexa6 hepta7 octa8 non9 deca10
• Use the general format shown below
• prefix-(except mono)-name the 1st element
  prefix-name the 2nd element ending with -ide
• Practice Problems Name the following molecules.
• N2O5 CO
  Cl4F7 SO3

charges
share
prefixes
carbon monoxide
tetrachlorine heptafluoride
sulfur trioxide
dinitrogen pentoxide
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• Writing Molecular Formulas
• The prefixes in the name tell you the of atoms
  of each element there are. (Those become the
  _________________ in the formula!)
• Practice Problems Write the formula for each
  molecule.
• nitrogen monoxide carbon tetrachloride
  diphosphorous pentoxide

subscripts
CCl4
P2O5
NO