Types of Bonding Lab Wrap Up

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Types of Bonding Lab Wrap Up
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What Do The Formulas Mean?

• Describe what elements make up the compound
• Also describes how many of each type of atom
  there are in the compound
• C2H2F4

What Elements Are Present
How many of each there are
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More Complicated Formulae

• Formulae may have the same element more than
  once. This indicates something about the
  chemical structure, which we will learn about in
  Unit 5.
• For example NH4OH

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More Complicated Formulae

• Formulae may have parentheses
• For example Al(NO3)3
• The number outside the parentheses applies to
  each of the atoms in the parentheses

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How Many of Each Atom Are In A Formula?

• C3H8O
• MgSO4
• Ca(OH)2
• NH4NO3
• Mg3(PO4)2
• Fe(NO3)3

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What Does Conductivity Mean?

• How well a solution conducts electricity
• What do you need to conduct electricity?
• To conduct electricity you need moving charges
• Things with high conductivities have lots of
  things with charges that can move.

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A Few Conductivity Terms

• Electrolyte a compound that conducts
  electricity when dissolved in water.
• Strong electrolyte conducts electricity well
• Weak electrolyte conducts electricity slightly
• Non-electrolyte does not conduct electricity

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What does the Melting Point mean?

• When a compound changes states some of the forces
  that attract the various pieces together are
  broken.
• Low melting points indicate weak attractions
  between the little bits.

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What Does Appearance Mean?

• Regular Shapes are very important in science
• A Regular Shape at the visible level means that
  there is a very Regular Shape at the microscopic
  and atomic levels.

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Types of Chemical Bonding

• What Makes Salt, Aspirin, and Zinc Have Such
  Different Properties?

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Things Like Sodium Chloride

• High Melting Points
• Do Not Conduct Electricity in Solid Form
• Conduct Electricity in Solution
• Have a regular shape
• Made from a metal and a nonmetal (ex. NaCl)

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Things Like Sodium Chloride

• Metal loses electrons while nonmetal gains
  electrons (Na and Cl-)
• Make ions charged things
• Opposite Charges Attract
• Have a regular crystal structure
• Crystals come from a repeating pattern of ions.

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Things Like Sodium Chloride

• Pattern of ions repeats billions of times in a
  single crystal CRYSTAL LATTICE
• Has no specific number of atoms in crystal so we
  use an empirical formula
• Empirical formula - Lowest whole number ratio of
  atoms
• Call these compounds salts

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Things Like Sodium Chloride

• When melted, ions are freed from the crystal
  lattice structure
• Melting requires breaking the bonds holding the
  compound together
• Bonds are strong
• Therefore, melting point is high.

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IONIC BONDING

• Bonding between ions
• Atoms give and take electrons
• Transfer electrons
• Things like Salt

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Things Like Aspirin

• Low Melting Points
• Do Not Conduct Electricity in Solid Form
• Most Do Not conduct electricity in aqueous
  solution (some compounds in this category do a
  little bit)
• Have an irregular shape
• Made from all nonmetals (ex. C9H8O4)

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Things Like Aspirin

• Atoms share pairs of electrons between each other
  (potluck dinner)
• Shared electrons hold the atoms together

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Things Like Aspirin

• Smallest units have a distinct beginning and a
  distinct end MOLECULE
• Has a specific number of atoms in the molecule
  (ex. C9H8O4)

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Things Like Aspirin

• One line SINGLE BOND 2 electrons
• Two lines DOUBLE BOND 4 electrons
• Three lines TRIPLE BOND 6 electrons

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Things Like Aspirin

• When melted, bonds between atoms do NOT break
• Instead, attractive forces between molecules
  break.
• Intermolecular Forces
• Intermolecular forces are weak compared to bonds.
• Melting point is low.

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COVALENT BONDING

• Atoms Share Electrons to Make a Compound
• Things like Aspirin

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Things Like Zinc

• High Melting Points
• DO conduct electricity in the solid state
• Dont form aqueous solutions
• Have irregular shape but are malleable
• Made from all metals (ex. Brass a mixture of
  copper and zinc)

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Metals

• Overlap of the electron cloud of the metal atoms
• Creates metal ions
• Electrons move freely through the whole piece of
  metal
• Sea of Electrons

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Things Like Zinc

• When metals melt, some of the attractions from
  the sea of electrons are broken.
• Bonds are broken.
• Melting point is high.

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Things Like Zinc

• Because of the sea of electrons metals
• Can have its shape changed MALLEABLE
• Can be pulled into wire DUCTILE
• Are shiny LUSTEROUS

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METALLIC BONDING

• A Sea of Electron Glue Holds Atoms Together
• Delocalized Electrons
• Things like Zinc