Chemical

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Chemical Bonding
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GOALS
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1. Compare contrast ionic and covalent bonds in
terms of electron position.
2. Predict formulas for stable binary ionic
compounds based on balance of charges.
4. Apply the Law of Conservation of Matter by
balancing the following types of chemical
equations Synthesis Decomposition Single
Replacement Double Replacement
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3
Why do Atoms Form Compounds?
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• Stability.
• What makes an atom stable?
• Full outer energy level.
• Eight.
• Chart page 576.

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4

• A Chemical Bond holds atoms together in a
  compound.
• Two basic types
• Ionic
• Covalent

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Ionic Bonding
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Transfer of electrons from one atom to another
atom.
Occurs between metals and nonmetals.
Remember Atoms need a full outer energy level to
be stable. EIGHT!
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Occurs between metals and nonmetals.
Metals are electron donors.
Non-metals are electron accepters.
Called compounds.
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OPPOSITS ATTRACT!
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Ionic Bonding
CLIP
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Covalent Bonding
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Occurs between nonmetals and nonmetals.
The sharing of electrons between atoms.
Called Molecules.
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Hydrogen and Fluorine
Hydrogen and Chlorine
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Single, Double, Triple
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Clip
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Unequal Sharing
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d
d_
Polar
When one atom has a greater positive charge
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• Ionic and Covalent Bonding Review Clip

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Covalent or Ionic?
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• BeO
• HCl
• NaF
• KCl
• H2O2
• N2
• Cl2

• CO2
• H2O
• NaCl
• MgCl2
• NO2
• Li2S
• NaF

clip
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Writing Chemical Formulas
Goals revisited
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• Writing chemical formulas is a shorthand way of
  indicating what a substance is made of. 
• These formulas also let you know how many atoms
  of each type are found in a molecule. 

The chemical formula for water is H2O.  Carbon
Dioxide is CO2.  Why does oxygen combine in
different ratios, in different compounds?  The
chemical formula for table salt is NaCl. Calcium
Chloride is CaCl2. Why does chlorine combine in
different ratios, in different compounds? 
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The simplest compounds are ones with only two
elements These are called binary KI, CO, H2O,
NaCl
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4 -4
Oxidation numbers
1
0
-2
Tell you how many electrons an atom must gain,
lose or share to become stable.
2
-1
-3
3
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Oxidation numbers
We can predict the ratio of atoms in ionic
compounds based on their oxidation numbers
1
-1
1 valence electron
K
Cl
7 valence electron
All compounds are neutral
Tells you how many electrons an atom must gain,
lose or share to become stable.
KCl
That means the overall charge is ZERO!
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1
-1
2
-1
Na
Br
Ca
Br
To make it ZERO, you need 1 Ca 2 Br.
NaBr
CaBr2
Subscripts show the number of atoms of that kind
in the compound
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Some elements have more than one oxidation number
(Chart p588)
3
-2
2
-2
Fe
O
Fe
O
Fe2O3
FeO
We call these elements- Multivalent Elements
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Now You Try writing Binary Ionic formulas
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• K Br
• Mg Cl
• Ca I
• K O
• K I
• Sr Br
• Na O

• Ga Br
• Fe2 O
• Fe3 O
• Cu2 F
• Cr3 O
• Mg O
• Al P

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Polyatomic Ions
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Groups of Covalently Bonded atoms that stay
together.
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Try thesep591
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• Na SO4
• Mg PO4
• Ca CO3
• Na OH
• Mg OH
• NH4 OH

• K PO4
• NH4 NO3
• H SO4
• Ca SO4
• K NO3
• Na PO4

Final Practice
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Naming Chemical Formulas
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Naming Binary Compounds and Molecules
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• Steps
• If it is Binary-
• Decide if it is an ionic or covalent bond.
• Metal- nonmetal..
• Ionic
• Nonmetal- nonmetal.
• Covalent

• Example
• NaCl

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If ionic .

• Examples
• NaCl
• K2O
• AlCl3
• BaF2
• KI
• Li2O

• Check to see if any elements are multivalent.
• If all single valent, write the name of the
  positive ion first.
• Write the root of the negative ion and add ide.

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If ionic .
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• Examples
• FeO
• Fe2O3
• CuO
• Cu2O
• PbCl4
• PbI2

• Check to see if any elements are multivalent.
• If multivalent ions, determine the oxidation
  number of the element.
• Use Roman numerals in parentheses after the name
  of the element.
• Write the root of the negative ion and add ide.

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If Covalent...
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• Use Greek prefix to indicate how many atoms of
  each element are in the molecule
• Add -ide to the more electronegative element

• Greek Prefixes
• 1- mono-
• 2- di-
• 3- tri-
• 4- tetra-
• 5- penta-
• 6- hexa-
• 7- hepta-
• 8- octa-

• Example
• NO
• Nitrogen Monoxide
• PCl3
• Phosphorous trichloride

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If it contains a polyatomic ion...
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• Write the name of the positive ion.
• Write the name of the polyatomic ion.

• Examples
• NaCO3
• KNO3
• NaC2H3O2

• Example
• KOH
• Potassium Hydroxide
• CaCO3
• Calcium Carbonate

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Name the following
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• CaSO4
• NH4OH
• CaCO3
• Cu(ClO3) 2
• Cr2O 3
• SrI 2
• CCl4

• KBr
• HCl
• MgO
• CaCl2
• H2O
• NO2
• CuSO4

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Writing Balancing Chemical Equations
Goals revisited
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Chemical Reactions
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• A chemical reaction is a change in which one or
  more substances are converted into new
  substances.
• Rearrangement of bonds in compounds and
  molecules.
• Chemical Equations make it possible to see
  clearly what is happening during a chemical
  reaction

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Chemical equations are a shorthand way to show
chemical reactions.
Reactants
Products
H2 O2
H2O
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Conservation of Mass
The mass of the products always equals the mass
of the reactants
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H2 O2
H2O
Does this meet the Conservation of Mass Law?
2 Hydrogen atoms
2 Oxygen atoms
2 Hydrogen atoms one Oxygen atom
Must Balance the Equation to show Conservation of
Mass.
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Can add coefficients to Balance equations.
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H2 O2
H2O
2
2
2
4
1
2
2
4
2
Balanced!!
Steps 1. Count Atoms on both sides
2. If not Balanced, add coefficients to balance.
3. Recount atoms after adding each coefficient.
4. Keep adding coefficients until balanced.
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Types of Chemical Reactions
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Chemical Reactions
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• You start with one or more compounds and turn it
  into different compounds.

Vapors of hydrogen chloride in a beaker and
ammonia in a test tube meet to form a cloud of a
new substance, ammonium chloride.
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• Synthesis
• Decomposition
• Single Replacement (Single Displacement)
• Double Replacement (Double Displacement)

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Synthesis
to make
A B AB
Cu O CuO
2H2 O2 2H2O
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Animation
Decomposition
to breakdown
AB A B
2H2O 2H2 O2
NaOH Na OH
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Single Replacement
When one element replaces another element in a
compound
A BC AC B
CuAgNO3 Cu(NO3)2 2Ag
The more reactive metal will always replace the
less reactive metal. (p749)
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Single Replacement
Animation

• Clip

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Double Replacement
Positive Ion of One compound replaces the
positive ion of another compound and a
Precipitate is formed.
AB CD AD CB
Ba(NO3)2K2SO4 BaSO4 2KNO3
Clip
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Clip
Animation
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Chemical Reactions and Energy
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Chemical Reactions and Energy
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• All chemical reactions release or absorb energy.
• Heat, light, sound
• Chemical reactions are the making and breaking or
  bonds.

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1. Exergonic

• Chemical reactions that releases energy are
  called exergonic.
• Glow sticks
• If heat is released, it is called exothermic.

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2. Endergonic

• Chemical reactions that require energy are called
  endergonic.
• Ex Cold Packs
• If heat is absorbed, it is called endothermic

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Catalysts and Inhibitors

• Some reactions proceed slowly.
• They can be sped up by a catalysts.
• Catalysts are not used up in the reaction.
• EX enzymes (biological catalysts)
• Some reactions proceed too fast.
• They can be slowed down by inhibitors.
• EX Preservatives in food

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GOALS Revisited..
1. Compare contrast ionic and covalent bonds in
terms of electron position.
2. Predict formulas for stable binary ionic
compounds based on balance of charges.
4. Apply the Law of Conservation of Matter by
balancing the following types of chemical
equations Synthesis Decomposition Single
Replacement Double Replacement