Chemical Bonding and Nomenclature

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Chemical Bonding and Nomenclature
2
s
Chemical
Bond
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Bonding, the way atoms are attracted to each
other to form molecules, determines nearly all of
the chemical properties we see. And, as we know,
the number 8 is very important to chemical
bonding.
I want you to meet a friend of mine?
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What are Molecules?
Molecules are a combination of atoms bonded
together (compounds) Bonding determines the
chemical properties of the molecule (compound).
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3 Kinds of Chemical Bonds
IONIC COVALENT METALLIC
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Ionic Bonds -Being Like the Noble Gases
All atoms want to have the same number of
electrons as the Noble Gases. The Noble Gases
have very stable electron configurations.
Metals- positive charge lose electrons
become cations Non-Metals- negative charge -
gain electrons become anions
Al becomes Al3
Mg becomes Mg2
Na becomes Na
Cl becomes Cl-
O becomes O-2
N becomes N-3
Ionic Bonding because opposite ions attract
The positive and negative ions are attracted to
each other electrostatically.
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Opposites Attract!
http//ed.ted.com/lessons/how-atoms-bond-george-za
idan-and-charles-morton
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How do we know how many atoms of each in an ionic
bond?You did this yesterdayIoinic Compounds are
stable NEUTRAL
Negative charge must equal the positive
chargeLets Use the Criss-Cross Method!
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Putting Ions Together
To get equal cations and anions in an ionic
compound, you need to show how many of each Ca2
F -1 Now I know we will need two F ions
to match the Ca ion CaF2 Subscripts The
number that tells how many atoms/ions are in the
formula
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Ion Formulas
To get equal cations and anions in an ionic
compound, you need to show how many of each Ca2
F -1 criss-cross Now I know we will
need two F ions to match the Ca ion writtten like
this CaF2 Subscripts The number
that tells how many atoms / ions are in the
formula
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Ion Formulas
Remember those polyatomic ions (poly-many
atomic-atoms) They stay whole in compounds, need
more than one, must do so for whole ion Ca2
PO4 -3 cc Written like this
Ca3(PO4)2
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Putting Ions Together-Formulas
You try these!
Li Br -
MgF2
LiBr
Mg2 F -
KCl
NH4 PO4-3
K Cl -
(NH4)3PO4
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Practice

• Use Criss Cross Strategy
• You will need periodic table

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Naming Compounds

• Metals name goes first (cation) do not change
  it except Iron Ferrous
• Non-metal (anion) name is changed
• End of original name taken off and replaced with
  ide oxygen oxide
  nitrogen nitride flourine
  flouride
• REMEMBER Polyatomics stay as is, no name change

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Naming Examples

• Al2S3
• Aluminum and Sulfur
• Aluminum Sulfide
• Fe2O3
• Ferrous (Iron) and Oxygen
• Ferrous Oxide

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The Covalent Bond

• Atoms can form molecules by sharing electrons.
• Covalent Bonding bonding by sharing electrons
• This is done only among non-metal atoms.

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Covalent Bonds continued
Remember the Lewis Dot diagram- shows the valence
electrons.helps us show how covalent bonds form
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Let's Try it!
Hydrogen and Oxygen
4 NB
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Let's Try it!
Hydrogen and Nitrogen
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Let's Try it!
Carbon and Oxygen
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Naming compounds covalent

• Element furthest on the left of the periodic
  table named first
• 2nd elements last letters replaced with ide
  (example chlorine -gt chloride)
• Use Greek prefixes for the number of atoms (mono,
  di, tri, tetra, penta, hexa, hepta, octa, nona,
  deca) Dont use mono if only one atom of first
  element.

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Lets Practice!
Name the following.
PH3 CO HI N2O3
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Characteristics of Ionic compounds

• At room temperature, most are crystals
• Dissolve well in water, but NOT in a non-polar
  liquid
• High melting/boiling points
• Can conduct electricity when melted

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Covalent bonds/compounds

• Sometimes crystals, sometimes gases, sometimes
  liquids. Wider range of forms.
• Have lower melting and boiling points than ionic
  compounds
• Many dont dissolve well in water dissolve well
  in nonpolar liquids
• Dont conduct electricity in water

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Polyatomic Ions(partial list from page 195 (193
2nd edition))

• Ammonium...
• Nitrate
• Permanganate. .
• Chlorate
• Hydroxide.
• Cyanide.
• Sulfate...
• Carbonate.
• Chromate..
• Acetate..
• Phosphate.

• NH4
• NO3-
• MnO4-
• ClO3-
• OH-
• CN-
• SO4 2 -
• CO32-
• CrO42-
• C2H3O2-
• PO43-