Chemistry Unit 6 Part 1

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Chemistry Unit 6 Part 1
Ionic Bonds

• Chemical Bonding Ionic Bonds

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Why Do Atoms Bond?

• To become more stable
• like the noble gases.
• Octet Rule atoms tend to gain, lose or share
  electrons in order to acquire a full shell of
  valence electrons. (usually 8)

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Three Main Types of Bonds

• Ionic Bond Atoms transfer electrons to fill
  their valence shells, oppositely charged ions
  are formed, opposites attract.
• Occurs between a metal and a nonmetal
• Covalent Bond Atoms share electrons to fill
  their valence shells.
• Occurs between nonmetals
• Metallic Bonds Atoms share a sea of
  electrons.
• Occurs between atoms of a metal

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Ionic Bond
Atoms transfer electrons to fill their valence
shells, oppositely charged ions are formed,
opposites attract
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Ionic Bonding
Na

• Ion a charged particle
• An ion can be positive or negative
• A neutral atom becomes an ion when it loses or
  gains one or more electrons to get a full outer
  shell of valence electrons remember Eight is
  Great

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Ionic Bonding

• If an atom loses an electron, it becomes a
  positive () ion called a cation. Ex when
  sodium loses one electron, its oxidation number
  becomes 1 and its ionic notation is Na 1
• If an atom gains an electron, it becomes a
  negative (-) ion called an anion. Ex when
  chlorine gains one electron its oxidation number
  becomes -1 and its ionic notation is Cl -1

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Ionic Compound NaCl
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Ionic Bonding

• Example

Na
Cl
To become more stable, sodium must lose one
electron
To become more stable, chlorine must gain one
electron
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Ionic Bonding

• Example

Sodium loses an electron and becomes an Na1 ion.
Chlorine gains an electron and becomes a Cl-1 ion.
Opposites attract, and an ionic compound is
formed NaCl
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Ionic Bonds Solids w/ Lattice
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Try Another Example
Br
Al
Aluminum will become more stable if it gets rid
of three electrons.
Bromine will become more stable if it receives
one electron.
Are both atoms more stable as a result of this
transfer? No, Al must donate two more where?
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Aluminum Bromine
Now, each atom has a full valence shell all are
more stable.
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Aluminum and Bromine
Aluminum donated 3 e-, so it becomes Al3
Each bromine accepted 1 e-, so they each become
Br-1
The compound that forms is AlBr3
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Aluminum Oxygen Al2O3
Ruby
Sapphire
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Lets Wrap it Up

• Ionic bonds are held together by electrostatic
  forces, that is, opposites charges attract.
• The result of an ionic bond is called an ionic
  compound.
• Ionic bonds form between a metal and a nonmetal
  atom due to large differences in
  electronegativity (EN). (from Table 1.7 or more)
• The nonmetals EN is so much greater than the
  metals, that it removes the electrons, forming
  oppositely charged ions!

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For Example Na and O
EN of Na 0.9 EN of O 3.5
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Why do Sodium and Oxygen form an ionic bond?

• 3.5 EN of O
• - 0.9 EN of Na
• 2.4 Difference in EN
• Difference in electronegativity is 2.4(gt1.7)
• An ionic bond will form.
• Oxygen has a greater electronegativity, and is
  able to yank electrons away from sodium.

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Writing Ionic Formulas

• Calcium Chloride
• Locate the metal on the periodic table and write
  the element symbol with its oxidation number.
• Ca 2

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Writing Ionic Formulas

• Locate the nonmetal on the periodic table and
  write the elements symbol with its oxidation
  number.
• Cl-1

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Ca2 Cl-1

• Find the common factor between the two oxidation
  numbers.
• In this case, 2.
• Decide how many of each ion is needed to make the
  charge equal to the common factor.
• In this case, 1 calcium ion (2) and 2 chlorine
  ions (-1 and 1 -2). Compounds are neutral.
• Use this number of ions as the subscript for the
  element, and write the formula.
• In this case, Ca Cl2.

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Writing Ionic Formulas Part 2

• Aluminum Oxide
• Locate the metal on the periodic table and write
  the element symbol with its oxidation number.
• Al 3

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Writing Ionic Formulas Part 2

• Locate the nonmetal on the periodic table and
  write the elements symbol with its oxidation
  number.
• O-2

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Al3 O-2

• Find the common factor between the two oxidation
  numbers.
• In this case, 6.
• Decide how many of each ion is needed to make the
  charge equal to the common factor.
• In this case, 2 aluminum ions (3 and 3 6)
  and 3 oxygen ions (-2 and -2 and -2 -6).
  Compounds are neutral.
• Use this number of ions as the subscript for the
  element, and write the formula.
• In this case, Al2O3.

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Try these examples on your own.

• Sodium and Oxygen
• Lithium and Sulfur
• Aluminum and Chlorine
• Potassium and Nitrogen
• Magnesium and Fluorine

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Naming Ionic Compounds

• Write the name of the metal.
• Write the name of the nonmetal with the ending
  changed to ide.
• Example
• Nitrogen nitride Sulfur sulfide
• Oxygen oxide Chlorine chloride
• Phosphorus phosphide Iodine iodide
• Fluorine fluoride Bromine bromide

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Naming Ionic Compounds

• Al2S3
• Write the name of the metal.
• Aluminum
• Write the name of the nonmetal, changing the
  ending to ide.
• Sulfide
• Name the compound.
• Aluminum Sulfide

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Naming Ionic Compounds

• BaCl2
• Write the name of the metal.
• Barium
• Write the name of the nonmetal, changing the
  ending to ide.
• Chloride
• Name the compound.
• Barium Chloride

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Try these examples on your own.

• BeF
• Li20
• B2S3
• Mg3N2
• CaCl2