Chapter 5: Soap

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Chapter 5 Soap
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Introductory Activity

• Fill a test tube with an inch of water
• Add a squirt of cooking oil to the test tube.
  Observe
• Stopper, shake observe
• Add a few drops of soap. Observe
• Stopper, shake observe
• With another test tube, add water soap only.
  Observe.
• Compare the two test tubes.
• Make particle visualizations describing each test
  tube.

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Introductory Activity

• What ideas do you have about how soap works?
• What kinds of things do advertising and marketing
  tell you?
• What do the soap companies want you to know about
  how soap works?

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Soap

• This chapter will introduce the chemistry needed
  to understand how soap works
• Section 5.1 Types of bonds
• Section 5.2 Drawing Molecules
• Section 5.3 Compounds in 3D
• Section 5.4 Polarity of Molecules
• Section 5.5 Intermolecular Forces
• Section 5.6 Intermolecular Forces and Properties

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Soap
Inter-molecular forces
Molecular Geometry
Bonding types Structures
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Section 5.1Types of Bonds
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Why atoms bond

• Atoms are most stable when theyre outer shell of
  electrons is full
• Atoms bonds to fill this outer shell
• For most atoms, this means having 8 electrons in
  their valence shell
• Called the Octet Rule
• Common exceptions are Hydrogen and Helium which
  can only hold 2 electrons.

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One way valence shells become full
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Cl
Na
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Sodium has 1 electron in its valence shell
Chlorine has 7 electrons in its valence shell
Some atoms give electrons away to reveal a full
level underneath. Some atoms gain electrons to
fill their current valence shell.
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One way valence shells become full
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Cl
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The sodium now is a cation (positive charge) and
the chlorine is now an anion (negative
charge). These opposite charges are now
attracted, which is an ionic bond.
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Ionic BondingMetal Non-metal

• Metals have fewer valence electrons and much
  lower ionization energies (energy needed to
  remove an electron) than non-metals
• Therefore, metals tend to lose their electrons
  and non-metals gain electrons
• Metals become cations (positively charged)
• Non-metals become anions (negatively charged)
• The cation anion are attracted because of their
  chargesforming an ionic bond

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Bonding between non-metals

• When two non-metals bond, neither one loses or
  gains electrons much more easily than the other
  one.
• Therefore, they share electrons
• Non-metals that share electrons evenly form
  non-polar covalent bonds
• Non-metals that share electrons un-evenly form
  polar covalent bonds

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Metals bonding

• Metals form a pool of electrons that they share
  together.
• The electrons are free to move throughout the
  structurelike a sea of electrons
• Atoms arent bonded to specific other atoms, but
  rather to the network as a whole

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Bond type affects properties

• The type of bonding affects the properties of the
  substance.
• There are always exceptions to these
  generalizations (especially for very small or
  very big molecules), but overall the pattern is
  correct

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Melting/Boiling Points

• Ionic bonds tend to have very high
  melting/boiling points as its hard to pull apart
  those electrostatic attractions
• Theyre found as solids under normal conditions
• Polar covalent bonds have the next highest
  melting/boiling points
• Most are solids or liquids under normal
  conditions
• Non-polar covalent bonds have lower
  melting/boiling points
• Most are found as liquids or gases

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Solubility in Water

• Ionic polar covalent compounds tend to be
  soluble in water
• Non-polar metallic compounds tend to be
  insoluble

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Conductivity of Electricity

• In order to conduct electricity, charge must be
  able to move or flow
• Metallic bonds have free-moving electronsthey
  can conduct electricity in solid and liquid state
• Ionic bonds have free-floating ions when
  dissolved in water or in liquid form that allow
  them conduct electricity
• Covalent bonds never have charges free to move
  and therefore cannot conduct electricity in any
  situation