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 unit for aluminum oxide.
  The subscripts indicate how many ions are needed
  of each in order to balance the charges.
• The formula unit consists of 2Al3 ions and 3O2-
  ions. (6 positive charges cancel out 6 negative
  charges resulting in a neutral compound)

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Try a few

• Potassium and Iodide
• K1 I1- ? KI
• Magnesium and chloride
• Mg2 Cl1- ? MgCl2
• Aluminum and bromide
• Al3 Br1- ? AlBr3
• Cesium and nitride
• Cs1 N3- ? Cs3N

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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).
• Note Cations that are not located in groups 1A,
  2A, or 3A, require a roman numeral.

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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
• Note Cris cross the subscripts back up to
  determine the charges Fe3N2 Fe2N3-

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Lets practice

• CaCl2
• Calcium chloride
• K2O
• Potassium oxide
• CuCl2
• Copper (II) chloride
• Fe2O3
• Iron (III) oxide

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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

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Examples

• Write the formula for copper (II) sulfate.
• Cu2
• Look up sulfate on the table and record the
  formula
• SO42-
• Apply the cris cross method as usual.
• Cu2SO42- ? CuSO4

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Another Example

• Iron (II) nitrate
• Fe2
• Look up nitrate on the table
• NO31-
• Apply the cris cross method as usual
• Fe2NO31- ? Fe(NO3)2

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Naming compounds containing polyatomic ions

• Write the name for Al2(SO4)3
• name the cation
• Look up the polyatomic ion on the table and write
  its name (Do not change the ending)
• aluminum sulfate
• Try this one Na3PO4
• Sodium phosphate

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Metallic Compounds

• Compounds containing only metals
• Form lattice crystals as solids

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Metallic Bonds

• Metals do not give away or take on valence
  electrons.
• They do not share electrons to make bonds either.
  
• Electrons from metals overlap and create a sea of
  electrons that bond metal atoms

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Metallic Bonds

• The electrons are free to move between atoms
  (delocalized electrons)
• As an electron moves from one atom to the next it
  creates a cation which bonds the atoms together
  creating a metallic bond.

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Properties of Metals

• Metals Usually have high melting points.
• Metals usually have high boiling points
• Why?

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Properties of Metals

• Malleable- ability to be hammered into a thin
  sheet
• Ductile- ability to be stretched into a thin wire
• Durable-long lasting
• Why?

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Properties of Metals

• Good conductors of heat
• Good conductors of electricity
• Why?

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Properties of Metals

• Metals are strong and hard
• Why?

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Alloys

• Alloys are mixtures of metals
• Ex stainless steel, brass, cast iron
• Properties of alloys are similar to those of its
  elements. Alloys tend to be stronger than the
  element