MOLECULAR%20SHAPES

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IONIC BONDING
2
IONIC BONDING
When an atom of a nonmetal takes one or more
electrons from an atom of a metal so both atoms
end up with eight valence electrons
3
IONIC BONDING
IS THE COMPOUND AN IONIC COMPOUND?
Mg N
3
2
4
IONIC BONDING

• Metals will tend to lose electrons and become
• POSITIVE CATIONS

5
IONIC BONDING

• Nonmetals will tend to gain electrons and become
• NEGATIVE ANIONS

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IONIC BONDING
SODIUM SULFATE
7
Crystalline structure
The POSITIVE CATIONS stick to the NEGATIVE
ANIONS, like a magnet.


-
-
-

-

-


-

-
-


-
8
COVALENT BONDING
9
COVALENT BONDING
When an atom of one nonmetal shares one or more
electrons with an atom of another nonmetal so
both atoms end up with eight valence electrons
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COVALENT BONDING
IS THE COMPOUND A COVALENT COMPOUND?
C O
2
YES since it is made of only nonmetal elements
11
Covalent bonding

• Fluorine has seven valence electrons

12
Covalent bonding

• Fluorine has seven valence electrons
• A second atom also has seven

13
Covalent bonding

• Fluorine has seven valence electrons
• A second atom also has seven
• By sharing electrons

14
Covalent bonding

• Fluorine has seven valence electrons
• A second atom also has seven
• By sharing electrons

15
Covalent bonding

• Fluorine has seven valence electrons
• A second atom also has seven
• By sharing electrons

16
Covalent bonding

• Fluorine has seven valence electrons
• A second atom also has seven
• By sharing electrons

17
Covalent bonding

• Fluorine has seven valence electrons
• A second atom also has seven
• By sharing electrons

18
Covalent bonding

• Fluorine has seven valence electrons
• A second atom also has seven
• By sharing electrons
• Both end with full orbitals

19
Covalent bonding

• Fluorine has seven valence electrons
• A second atom also has seven
• By sharing electrons
• Both end with full orbitals

F
F
8 Valence electrons
20
Covalent bonding

• Fluorine has seven valence electrons
• A second atom also has seven
• By sharing electrons
• Both end with full orbitals

F
F
8 Valence electrons
21
Single Covalent Bond

• A sharing of two valence electrons.
• Only nonmetals and Hydrogen.
• Different from an ionic bond because they
  actually form molecules.
• Two specific atoms are joined.
• In an ionic solid you cant tell which atom the
  electrons moved from or to.

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Water

• Each hydrogen has 1 valence electron
• Each hydrogen wants 1 more
• The oxygen has 6 valence electrons
• The oxygen wants 2 more
• They share to make each other happy

23
Water

• Put the pieces together
• The first hydrogen is happy
• The oxygen still wants one more

H
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Water

• The second hydrogen attaches
• Every atom has full energy levels

H
H
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Carbon dioxide

• Hybridization of Carbon!
• CO2 - Carbon is central atom ( I have to tell
  you)
• Carbon has 4 valence electrons
• Wants 4 more
• Oxygen has 6 valence electrons
• Wants 2 more

C
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Carbon dioxide

• Attaching 1 oxygen leaves the oxygen 1 short and
  the carbon 3 short

C
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Carbon dioxide

• Attaching the second oxygen leaves both oxygen 1
  short and the carbon 2 short

C
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Carbon dioxide

• The only solution is to share more

C
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Carbon dioxide

• The only solution is to share more

C
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Carbon dioxide

• The only solution is to share more

C
O
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Carbon dioxide

• The only solution is to share more

C
O
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Carbon dioxide

• The only solution is to share more

C
O
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Carbon dioxide

• The only solution is to share more

C
O
O
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Carbon dioxide

• The only solution is to share more
• Requires two double bonds
• Each atom gets to count all the atoms in the bond

C
O
O
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Carbon dioxide

• The only solution is to share more
• Requires two double bonds
• Each atom gets to count all the atoms in the bond

8 valence electrons
C
O
O
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Carbon dioxide

• The only solution is to share more
• Requires two double bonds
• Each atom gets to count all the atoms in the bond

8 valence electrons
C
O
O
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Carbon dioxide

• The only solution is to share more
• Requires two double bonds
• Each atom gets to count all the atoms in the bond

8 valence electrons
C
O
O
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How to draw them

1. Add up all the valence electrons.
2. Count up the total number of electrons to give
   all atoms full outer shells.
3. Subtract 1 from 2.
4. Divide by 2
5. Tells you how many bonds - draw them.
6. Fill in the rest of the valence electrons to fill
   atoms up.

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Examples
N

• NH3
• N - has 5 valence electrons wants 8
• H - has 1 valence electrons wants 2
• NH3 has 53(1) 8
• NH3 wants 83(2) 14
• (14-8)/2 3 bonds
• 4 atoms with 3 bonds

H
40
Examples

• Draw in the bonds
• All 8 electrons are accounted for
• Everything is full

H
N
H
H
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Examples

• HCN C is central atom
• N - has 5 valence electrons wants 8
• C - has 4 valence electrons wants 8
• H - has 1 valence electrons wants 2
• HCN has 541 10
• HCN wants 882 18
• (18-10)/2 4 bonds
• 3 atoms with 4 bonds -will require multiple bonds
  - not to H

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HCN

• Put in single bonds
• Need 2 more bonds
• Must go between C and N

N
H
C
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HCN

• Put in single bonds
• Need 2 more bonds
• Must go between C and N
• Uses 8 electrons - 2 more to add

N
H
C
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HCN

• Put in single bonds
• Need 2 more bonds
• Must go between C and N
• Uses 8 electrons - 2 more to add
• Must go on N to fill octet

N
H
C
45
Another way of indicating bonds

• Often use a line to indicate a bond
• Called a structural formula
• Each line is 2 valence electrons

H
H
O
H
H
O

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Structural Examples

• C has 8 electrons because each line is 2
  electrons
• Ditto for N
• Ditto for C here
• Ditto for O

H C N
H
C O
H
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Coordinate Covalent Bond

• When one atom donates both electrons in a
  covalent bond.
• Carbon monoxide
• CO

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Coordinate Covalent Bond

• When one atom donates both electrons in a
  covalent bond.
• Carbon monoxide
• CO

O
C
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Coordinate Covalent Bond

• When one atom donates both electrons in a
  covalent bond.
• Carbon monoxide
• CO

O
C
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Polar Bonds

• When the atoms in a bond are the same, the
  electrons are shared equally.
• This is a nonpolar covalent bond.
• When two different atoms are connected, the atoms
  may not be shared equally.
• This is a polar covalent bond.
• How do we measure how strong the atoms pull on
  electrons?

51
Electronegativity

• A measure of how strongly the atoms attract
  electrons in a bond.
• The bigger the electronegativity difference the
  more polar the bond.
• 0.0 - 0.3 Covalent nonpolar
• 0.3 - 1.67 Covalent polar
• gt1.67 Ionic

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How to show a bond is polar

• Isnt a whole charge just a partial charge
• d means a partially positive
• d- means a partially negative
  
• The Cl pulls harder on the electrons
• The electrons spend more time near the Cl

d
d-
H
Cl
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Polar Molecules

• Molecules with ends

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Polar Molecules

• Molecules with a positive and a negative end
• Requires two things to be true
• The molecule must contain polar bonds
• This can be determined from differences in
  electronegativity.
• Symmetry can not cancel out the effects of the
  polar bonds.
• Must determine geometry first.

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Is it polar?

• HF
• H2O
• NH3
• CCl4
• CO2

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Intermolecular Forces

• What holds molecules to each other

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Intermolecular Forces

• They are what make solid and liquid molecular
  compounds possible.
• The weakest are called van der Waals forces -
  there are two kinds
• Dispersion forces
• Dipole Interactions
• depend on the number of electrons
• more electrons stronger forces
• Bigger molecules

58
Dipole interactions

• Depend on the number of electrons
• More electrons stronger forces
• Bigger molecules more electrons
• Fluorine is a gas
• Bromine is a liquid
• Iodine is a solid

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Dipole interactions

• Occur when polar molecules are attracted to each
  other.
• Slightly stronger than dispersion forces.
• Opposites attract but not completely hooked like
  in ionic solids.

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Dipole interactions

• Occur when polar molecules are attracted to each
  other.
• Slightly stronger than dispersion forces.
• Opposites attract but not completely hooked like
  in ionic solids.

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Dipole Interactions
d d-
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Hydrogen bonding

• Are the attractive force caused by hydrogen
  bonded to F, O, or N.
• F, O, and N are very electronegative so it is a
  very strong dipole.
• The hydrogen partially share with the lone pair
  in the molecule next to it.
• The strongest of the intermolecular forces.

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Hydrogen Bonding
64
Hydrogen bonding
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MOLECULAR SHAPES

• OF
• COVALENT COMPOUNDS

66
VSepR tHEORY
ALENCE
HELL
VSEPR
LECTRON
AIR
EPULSION
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What Vsepr means
Since electrons do not like each other, because
of their negative charges, they orient themselves
as far apart as possible, from each other.
This leads to molecules having specific shapes.
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Things to remember

• Atoms bond to form an Octet (8 outer
  electrons/full outer energy level)
• Bonded electrons take up less space then
  un-bonded/unshared pairs of electrons.

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HERE ARE THE RESULTING MOLECULAR SHAPES
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Linear
EXAMPLE BeF2

• Number of Bonds 2
• Number of Shared Pairs of Electrons 2
• Bond Angle 180

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Trigonal Planar
EXAMPLE GaF3

• Number of Bonds 3
• Number of Shared Pairs of Electrons 3
• Number of Unshared Pairs of Electrons 0
• Bond Angle 120

72
Bent 1
EXAMPLE H2O

• Number of Bonds 2
• Number of Shared Pairs of Electrons 2
• Number of Unshared Pairs of Electrons 2
• Bond Angle lt 120

73
Bent 2
EXAMPLE O3

• Number of Bonds 2
• Number of Shared Pairs of Electrons 2
• Number of Unshared Pairs of Electrons 1
• Bond Angle gt120

74
Tetrahedral
EXAMPLE CH4

• Number of Bonds 4
• Number of Shared Pairs of Electrons 4
• Number of Unshared Pairs of Electrons 0
• Bond Angle 109.5

75
Trigonal Pyramidal
EXAMPLE NH3

• Number of Bonds 3
• Number of Shared Pairs of Electrons 4
• Number of Unshared Pairs of Electrons 1
• Bond Angle lt109.5

76
Trigonal bIPyramidal
EXAMPLE NbF5

• Number of Bonds 5
• Number of Shared Pairs of Electrons 5
• Number of Unshared Pairs of Electrons 0
• Bond Angle lt120

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OCTAHEDRAL
EXAMPLE SF6

• Number of Bonds 6
• Number of Shared Pairs of Electrons 6
• Number of Unshared Pairs of Electrons 1
• Bond Angle 90

78
Metallic Bonds

• How atoms are held together in the solid.
• Metals hold onto there valence electrons very
  weakly.
• Think of them as positive ions floating in a sea
  of electrons.

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Sea of Electrons

• Electrons are free to move through the solid.
• Metals conduct electricity.

80
Metals are Malleable

• Hammered into shape (bend).
• Ductile - drawn into wires.

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Malleable
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Malleable

• Electrons allow atoms to slide by.

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THE END