Ionic Compounds and Metals

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Ionic Compounds and Metals
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Types of bonds

• A chemical bond is the force that holds atoms
  together in a molecule.
• Ionic bonds form when electrons are transferred
  between atoms.
• Covalent bonds form when electrons are shared
  between atoms.

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Electronegativity

• Electronegativity is a measure of the attraction
  a bonded atom has for electrons.
• Electronegativity increases from bottom to top
  and from left to right.

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Formation of Ionic Bonds

• If the electronegativity difference is large (a
  metal with a nonmetal) an ionic bond will form.
• Ionic bonds are the strongest type of bond.
• Substances resulting from ionic bonds are
  classified as crystalline solids.

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Lets Practice

• Identify the type of bond (ionic or covalent)
  that will form between each pair of atoms.
• Na and Cl
• C and O
• N and H
• Ca and O
• K and N
• Mg and F

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Example
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Forming Ions

• When neutral atoms gain or lose valence e- an ion
  is formed.
• Ions are atoms with a charge
• Cations have a positive charge (K, Li)
• Anions have a negative charge (F-, I-)

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Ions forming bonds

• Cations are attracted to anions because of
  opposite charges.
• Opposites attract

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Why do ions form?

• Ions form to attain a more stable electron
  configuration.
• Remember that a Noble gas configuration is the
  most stable
• Ne - ___ ___ ___ ___ ___
• 1s 2s 2p
• All Noble Gases have a full octet (8 valence e-)

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Noble Gases
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Why do ions form?

• Na __ __ __ __ __ __
• 1s 2s 2p 3s
• Na __ __ __ __ __ __
• 1s 2s 2p 3s
• Now Na looks like neon
• Ne __ __ __ __ __
• 1s 2s 2p

• All atoms are trying to have a Noble Gas electron
  configuration so, they will lose or gain
  electrons to get there

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Why do ions form?

• F __ __ __ __ __
• 1s 2s 2p
• F- __ __ __ __ __
• 1s 2s 2p
• Ne __ __ __ __ __
• 1s 2s 2p

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Review

• Draw the dot notation for each element and the
  charge of its ion
• N
• S
• Ba
• Li

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Ionic Bonds

• Ionic bonds- the force that holds two oppositely
  ( and -) charged particles together.
• Ionic compounds contain ionic bonds and are
  neutral
• Usually forms between a metal and a nonmetal

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Forming Ionic Bonds
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Forming Ionic Compounds

• Write an equation showing how ionic compounds are
  formed for the following elements.
• Na and I
• Mg and O
• Al and Cl

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Properties of Ionic CompoundsShape

• The Ionic bond produces unique characteristics
  for ionic compounds
• Crystals are created by repeating patterns of
  cations and anions. This balances the forces
  between the ions.
• This is called a crystal lattice

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Properties of Ionic CompoundsPhysical Properties

• Electrolytes (aqueous ions- Ions dissolved in
  water) conduct electricity
• Solid ionic compounds DO NOT conduct electricity
  because the charges are locked in place

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Properties of Ionic CompoundsPhysical Properties

• Ionic solids are strong and hard to break apart
• High Melting points
• High Boiling points
• Transition metals in the crystal give the ionic
  solid color.

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Properties of Ionic CompoundsPhysical Properties

• The solid ionic crystals are hard, rigid, and
  brittle
• The strong forces between ions produce this
  property

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Ionic Compounds

• Ionic compounds are repeating patterns of the
  cation and anion.
• The simplest ratio of ions involved is called a
  formula unit.
• NaCl is the formula unit for table salt

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Ions in Ionic Compounds

• Monatomic ions- ions made of only one type of
  atom (Cl-, F-, Li)
• Polyatomic ions- ions made of at least two
  different types of ions (OH-, NH4)
• Cation Anion ? Ionic Compound

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Writing formulas for ionic compounds

• Binary ionic compounds contain a single cation
  and anion. Remember that the final compound must
  be neutral so the charges must balance.
• Ca2 Cl- ? CaCl2

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Cris-Cross method

• Record the ion symbol and charge
• The of the charge of the cation becomes the
  subscript for the anion and the of the charge
  for the anion becomes the subscript for the
  cation. The 1 does not have to be recorded it
  is understood.
• Al3 O-2 ? Al2O3

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Cris-Cross method

• Al2O3 is the formula units for aluminum oxide.
  The subscripts indicate how many ions are needed
  of each in order to balance the charges.

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Try a few

• Potassium and Iodide
• Magnesium and chloride
• Aluminum and bromide
• Cesium and nitride

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Naming Ionic Compounds

• NaBr
• Name the cation then the anion. Cations are
  always written first
• Monatomic cations always keep their name. If the
  cation is an ion that may carry multiple charges
  then a roman numeral is used to indicate which
  charge the cation is carrying. Fe3 (III) and
  Fe2 (II).

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Naming Ionic Compounds

• The monatomic anions ending is changed to -ide.
  Fluorine is changed to Fluoride.
• NaBr- sodium bromide
• Fe3N2 Iron (II) nitride

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Lets practice

• CaCl2
• K2O
• CuCl2
• Fe2O3

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What about Polyatomic ions?

• Al3 and PO4-3 ? AlPO4
• The same rules apply, however NEVER CHANGE A
  SUBSCRIPT THAT IS ALREADY THERE.
• Polyatomic ions may also require () around them
  if there is a need for more than one to balance
  the charge