22.2 Notes

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22.2 Notes Types of Bonds

• Part B

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Objectives

• Describe ionic and covalent bonds.
• Identify the particles produced by ionic bonding
  and by covalent bonding.
• Distinguish between a nonpolar covalent bond and
  an polar covalent bond.

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Covalent Bonds

• Occur when atoms share electrons
• Forms a molecule
• Share because losing electrons takes too much
  energy
• Single bonds sharing of 2 electrons
• Typically two elements each donating 1 electron
  to share
• Water contains 2 single bonds
• Each Hydrogen shares one electron with Oxygen
  sharing one electron

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Covalent Bonds

• A covalent bond can contain more than one pair of
  electrons
• Example Nitrogen (N2)
• Each nitrogen shares 3 electrons to form a triple
  bond

http//www.youtube.com/watch?vyjge1WdCFPs
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Unequal Sharing

• Electrons are not always shared equally
• Strength of attraction is related to size, charge
  and number of electrons
• One element has a stronger attraction
• Example HCl

Chlorine atoms have stronger attraction than
hydrogen
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Polar Molecule

• If charge is balanced but electrons are not
  shared equally, you have a polar molecule
• Polar molecules has a slightly positive end and
  a slightly negative end

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Nonpolar Molecule

• Molecule in which electrons are shared equally
• Does not have oppositely charged ends
• True of molecules made from two identical atoms
  or molecules that are symmetric

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http//www.elmhurst.edu/chm/vchembook/153Acompare
.html
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Properties of Compounds
Ionic Compounds Covalent Compounds
Bond Type Electron transfer Electron sharing
Smallest Particle Ion Molecule
Electrical Conductivity Good Poor
State at Room Temp Solid Any
Forces Between Particles Strong attraction between cations and anions Strong bonds between atoms, weak attraction between molecules
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Oxidation Number

• An oxidation number tells you how many electrons
  an atom has gained, lost, or shared to become
  stable
• For ionic compounds the oxidation number is the
  same as the charge on the ion
• For example, a sodium ion has a charge of 1 and
  an oxidation number of 1.

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1
2
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-3
-2
-1
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In-Class Assignment/Homework

• 22.1 22.2 Directed Reading
• 22.2 Reinforcement WKT