Covalent Bonding Notes

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Covalent Bonding Notes
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Ionic vs Covalent Bonding

• Ionic electron(s) leave one atom gained by
  another atom to satisfy both atoms octets, this
  results in the formation of ions. The resulting
  opposite charges attract each other.
• Covalent electrons are shared by two or more
  atoms to satisfy their octets.

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How can you tell if a bond is IONIC or COVALENT?

• Subtract the two electronegativity values (look
  at an electronegativity chart p. 263).
• gt1.7 to 4.0 Ionic
• gt0.4 to 1.7 Polar Covalent
• 0.0 to 0.4 Non-Polar
  Covalent
• Electronegativity atoms ability to attract
  electrons in a chemical bond. (higher
  electronegativity means the atom wants electrons
  more)

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How can you tell if a bond is IONIC or COVALENT?

• Easy way
• All metals metallic bond
• Nonmetals and Metals ionic bond
• All nonmetals covalent bond

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Yes, there are 2 kinds of covalent bonds!

• Polar covalent the electrons are shared, but one
  atom is pulling on the electrons a lot more. The
  electrons spend more time around that atom.
• Nonpolar covalent the electrons are evenly
  shared between the two atoms.

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O(3.5) H (2.1) 1.4Polar covalent bond
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• The closer the elements are on the periodic
  table, their electronegativities are more
  similar more likely to form covalent bonds
• Farther away greater difference in
  electronegativity more likely to form ionic
  bonds.
• Metal nonmetal usually ionic
• Nonmetal nonmetal usually covalent.

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Properties of Covalent Compounds

• 1)  Covalent compounds generally have much lower
  melting and boiling points than ionic compounds. 
  
• 2)  Covalent compounds are soft and squishy
  (compared to ionic compounds, anyway).

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Properties, Contd

• 3)  Covalent compounds tend to be more flammable
  than ionic compounds.
• There are exceptions to this rule!
• 4)  Covalent compounds don't conduct electricity
  in water.

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Bond Dissociation Energy

• Bond dissociation energy energy required to
  break a covalent bond.
• Highest bond energy
  Lowest bond energy
• Hardest to break
  Easiest to break
• Triple Double Single
• Bond Bond Bond
• Shortest bond length
  Longest bond length
• Strongest Weakest

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How to Name Covalent Compounds

• 1. Name the first element
• (normal name)
• 2. Name the second element
• (root name -ide)
• 3. Add prefixes to indicate how many atoms of
  each element are in the molecule
• (Subscripts)
• Exception no need to use mono for first
  element. Example CO2 carbon dioxide

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Prefixes
Subscript prefix
1 Mono
2 Di-
3 Tri-
4 Tetra-
5 Penta-
6 Hexa-
7 Hepta-
8 Octa-
9 Nona-
10 Deca-
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Memorize these exceptions
Chemical formula name
H2O water
CH4 Methane
NH3 ammonia
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MEMORIZE THESE ACID NAMES
Acid Name
HCl Hydrochloric acid
H2SO4 Sulfuric acid
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Diatomics

• Diatomic elements are elements that do not exist
  singularly in nature because they are highly
  reactive.
• Which elements are the diatomics?
• HON, its the halogens!
• H2, O2, N2, F2, Cl2, Br2, I2