Collect the Crossword Puzzle Homework

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Collect the Crossword Puzzle Homework
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6.2 Covalent Bonding and Molecular Compounds.
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H2 Covalent Bond
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Covalent Bond Formation
E0
Potential Energy
H-H Distance
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Bond Formation
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Covalent Bonding (cont.)

• A point is reached where the attractive and
  repulsive forces are balanced and potential
  energy is at a minimum.
• Results in a stable covalent bond.

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Why Does Bonding Occur
A bond will form if the system can lower its
total energy in the process.
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Characteristics of the Covalent Bond

• Bond length is the average distance between two
  bonded atoms, that is, the distance of minimum
  potential energy.
• Bond energy is the energy required to break a
  chemical bond and form neutral atoms.

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Bonding Parameters (cont.)

• For H2, the bond length is 74 pm (1 picometer
  10-12 m).
• For H2, the bond energy is 436 kJ/mole.
• As bond length decreases the bond energy
  increases.

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Cl2

• Odyssey Screen 15 A

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Octet Rule

• Chemical compounds tend to form so that each
  atom, by gaining, losing or sharing electrons,
  has an octet of electrons in its highest occupied
  energy level.

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H2 Molecule

• H 1s1
• ?
• H 1s1
• ?
• Filled outer shell like Helium

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Octet Rule -- F2 Molecule

• F1s22s22p5
• ?? ?? ?? ?? ?
• F1s22s22p5
• ?? ?? ?? ?? ?

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Octet Rule -- HCl Molecule

• H1s1
• 
  ?
• Cl 1s22s22p63s23p5
• ?? ?? ?? ?? ?? ?? ?? ?? ?

1s
2s
2px
2py
3px
3py
3pz
2pz
3s
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Electron Dot Notation

• An electron-configuration notation in which only
  the valence electrons of an atom of a particular
  element are shown indicated by dots placed around
  the elements symbol.

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Electron Dot Notation
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Lewis Structures

• A build on electron dot notations and electron
  configuration notation
• For molecules.
• Most simply, a hydrogen atom, H2, is represented
  as H ? H

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Lewis Structure H2
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Lewis Structure

• Atomic symbols represent nuclei and inner-shell
  electrons
• Dot pairs or dashes represent electron pairs in
  covalent bonds
• Dots adjacent to only one atomic symbol represent
  unshared electrons.

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Lewis Structure -- Cl2

• Z 17
• Ne 3s23p5
• Dot Diagram?
• Cl2
• Note shared pair of electrons

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Lewis Structures (cont.)

• Note each Cl is surrounded by three pairs of
  electrons that are not involved in bonding but
  belong to the Chlorine.

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Lone Pair/Unshared Pair

• A pair of electrons that is not involved in
  bonding, but instead belongs exclusively to one
  atom.

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Structural Formula

• Indicates the kind, number, arrangement, and
  bonds of the atoms in a molecule. Ethane...C2H6