Alfred Bernhard Nobel

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Lecture 19
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Alfred Bernhard Nobel
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bio

• Alfred Bernhard Nobel (1833-1896),, manufactured
  nitroglycerine.
• explosion killed Nobel's brother, he became
  determined to tame the explosive.
• In 1866, he found that an absorbent earth called
  "kieselguhr" could sponge up considerable
  quantities of nitroglycerine.
• The dampened kieselguhr could be molded into
  sticks which were made safe to handle, but
  retained the power of nitroglycerine itself. This
  safe explosive Nobel called dynamite. He
  speculated that
• it would make war so horrible as to enforce
  peace. (Yah, right!)

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homework

• Read pages 199 to 207
• Page 207 1 - 13

Go over yellow sheet of compounds
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Quiz 19
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As any matter moves to a lower more stable
energy level energy is released
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The more stable an atom becomes the more energy
it gives off

• An atom that loses or gains an electron and
  becomes more stable ion it gives off energy and
  settles into its lower energy state. If the ion
  gets into a even lower energy level by falling
  into a crystal the energy given off is called
  lattice energy

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Unstable atoms can also become stable by sharing
electrons
Covalent bond
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As the atoms become stable their energy decreases
Fusion energy
This means that 436 kJ of energy is Released
when this Bond forms and that it Takes the same
436 kJ Amount of energy to Break the bond
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Remember that bond energy is the amount of energy
necessary to break a bond
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The shorter the bond length the higher the bond
energy
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As we saw the smaller the bond length the greater
the bond energy
Bond length is the distance between two nucleolus
at their lowest energy state
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So we have learned that The composition of ionic
bond is metal and nonmetalThe composition of
metallic bond is metal and metalthe composition
of covalent bond is nonmetal and nonmetal
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If the covalent bond is even then it is nonpolar
covalent

• If the covalent bond is uneven then it is polar
  covalent

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Properties of different bonds
Covalent Bond Sharing of electrons Weak
intermolecular bond
Metallic bond Sea of electrons Strong bond
Ionic Bond Positive and Negative ion
Strong bond
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To help visualize the electrons and how they move
during covalent bonding we use Lewis Dot
Structures
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The Lewis dot diagram is used to show the valence
shell electronic structures of atoms and
molecules
Note each side must contain one dot (electron)
and then double up
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The Lewis dot diagrams can also be used to
predict single double and triple bonds by
calculating Electron inventory
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A compound like C2H4I am telling you it exists
I am telling you it is stable
It is bonded in with octets
H 2 Everything else 8
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Note the number of unpaired electrons
If it is stable then each atom has an octet

• Count number of electrons available
• Place elements
• Circle octet for each element
• Check electrons used against available
• If it doesn't add up look for double bonds

If it exists then the atoms are attached
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Draw Lewis dot for

• CHCl3
• H2S
• SiF4
• CH3I
• ICl
• C2H6

• Count number of electrons available
• Place elements
• Circle octet for each element
• Check electrons used against available
• If it doesn't add up look for double bonds