Ionic Bonding and Metallic Bonding

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Ionic Bonding and Metallic Bonding

• Chapter 7

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Ions

• Essential Question
• How are the two types of ions formed, and how can
  you tell from the periodic table which elements
  will form which type of ion?

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Valence Electrons

• Valence electrons are electrons in the highest
  occupied energy level.
• Elements within each group behave similarly
  because they have the same number of valence
  electrons.

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Valence Electrons

• To find the number of valence electrons in a
  representative element, look at the group number.
• How many valence electrons do group 2A elements
  have?...group 7A?...group 15?

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Electron Dot Structures

• Electron Dot Structures are diagrams that show
  valence electrons as dots.
• As a general rule, only valence electrons are
  shown.

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The Octet Rule

• In forming compounds, atoms tend to achieve the
  electron configuration of a noble gas.

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Metals vs Non-Metals

• Metals tend to lose their valence electrons,
  leaving a complete octet in the next-lowest
  energy level.
• Non-metals tend to gain electrons (or to share
  electrons) to achieve a complete octet.

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Formation of Cations

• What makes an atom neutral?
• How are ions formed?
• What type of ion is formed by the loss of
  electrons?

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Naming Cations

• For metallic elements, the name of the cation is
  the same as the name of the element.
• Sodium forms the sodium cation (Na)
• Calcium forms the calcium cation (Ca2)

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Isoelectronic Elements

• Isoelectronic elements are elements that are
  identical in their electron configurations.
• They are NOT the same element, but have the same
  arrangement to their electrons.

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Compare Sodium Ion with Neon
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Compare Ca2 with Argon
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Compare Al3 with Neon
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Transition MetalsCannot Be Trusted!

• D-block metals can form more than one ion.
• For example Fe2 and Fe3
• Cu and Cu2
• Pb2 and Pb4
• Three can be trusted Silver
• Cadmium and Zinc

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Pseudo Noble Gas Electron Configurations

• What is the electron configuration of Ag?
• How many electrons would silver have to lose to
  attain a noble gas electron configuration?
• How many electrons does it actually lose? Why?

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Pseudo Noble GasElectron Configurations

• This configurations has a distinct pattern.
• It results in an ns2 np6 nd10 arrangement.
• Silver, cadmium and zinc are examples

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Formation of Anions

• What makes an atom neutral?
• How are ions formed?
• What type of ion is formed by the gain of
  electrons?

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Naming Anions

• For non-metallic elements, the name of the anion
  is different from the name of the element.
• The name of the anion ends in ide.
• Oxygen forms the oxide anion (O2-)
• Nitrogen forms the nitride anion (N3-)

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Halogens and Halide Ions

• Just as the Group 7A elements have a special
  name
• The Group 7A anions have a special name
• The halogens form the halide ions.

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Compare Chloride with Argon
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Compare Oxide with Neon
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Compare Nitride with Neon
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What About Carbon?

• How can carbon form a cation?
• How can carbon form an anion?
• Carbon does not typically form ions
• Losing 4, or gaining 4, electrons is asking a bit
  too much

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Are You Memorizing Your Polyatomic Ions?

• Noticing the patterns makes it easier
• What does adding H do to the charge?
• What does adding/subtracting an oxygen atom do to
  the name?

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Ionic Bonds and Ionic Compounds

• Essential Question
• How are ionic compounds formed and what three
  properties do they exhibit?

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Formation of Ionic Compounds

• Imagine a chance encounter between sodium and
  chlorine
• How many valence e- does sodium have? and
  chlorine?
• How many do each of them want?

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Ionic Bonds

• A bond is nothing more, nothing less, than an
  attraction between atoms that holds them together
  in the formation of a compound.
• Ionic bonds are attractions between two
  oppositely charged ions.

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Ionic Compounds

• Although made of ions, ionic compounds are
  electrically neutral.
• How is this possible?
• How does sodium combine with chlorine?
• How does calcium combine with chlorine?
• How does aluminum combine with chlorine?

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Ionic Compounds

• A chemical formula shows the kinds and numbers of
  atoms in the smallest representative unit of
  the substance.
• A formula unit is the lowest whole-number ratio
  of ions in an ionic compound.

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Properties of Ionic Compounds

• Most ionic compounds share certain
  characteristics in common
• Crystalline solids at room temperature
• High melting temperature
• Conduct electricity ONLY when melted or dissolved
• Ionic solids are brittle

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Ionic Solid Unstressed
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Ionic Solid Stressed
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Bonding In Metals

• Essential Question
• How can you model the valence electrons of
  metals, and how are characteristics of metals
  explained by this electron arrangement?

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Metallic Bonds

• The atoms of metals can be modeled as cations
  surrounded by a sea of mobile valence electrons.
• Metallic bonds are the attraction of these
  cations for neighboring, free-floating valence
  electrons.

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Properties of Metals

• The sea of mobile electrons model explains many
  characteristics of metals.
• Good conductors of heat and electricity
• Metals are ductile
• Metals are malleable
• Atoms are arranged in very compact, orderly
  patterns (they are crystalline).

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Alloys

• Mixtures composed of two or more metals.
• Brass copper and zinc
• Bronze tin and copper
• Sterling silver copper and silver