Chemical Bonds

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Chemical Bonds
Part 2
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The Rest of the Story

• Covalent Bonding
• Metallic Bonding

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COVALENT BOND
bond formed by the sharing of electrons
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Happens when

• Two non-metals are joined together
• When the atoms share electron pairs
• Octet rule is still in place
• Examples O2, CO2, C2H6, H2O, SiC

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Covalent bonds
Atoms share electrons to fill outer shells
Oxygen Atom

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Watch it Happen
Covalent Bonds
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Diatomic Elements

• Some atoms cannot be alone
• They must be combined with something so are often
  paired with another of the same
• H O F Br I N
  Cl
• H2 O2 F2 Br2 I2 N2
  Cl2
• These are always covalent

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Poles or No?

• Magnets have poles (north south)
• Batteries have poles (positive negative)
• The Earth has poles (north south)
• Some molecules have poles
• Still sharing but one part is more positive the
  other is more negative

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NON-POLAR COVALENT BONDS
when electrons are shared equally
H2 or Cl2
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POLAR COVALENT BONDS
when electrons are shared but shared unequally
H2O
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Polar Covalent Bonds Unevenly matched, but
willing to share
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An example
Water is a polar molecule because oxygen pulls
the electrons more than hydrogen. Therefore
oxygen is more negative than the hydrogens.
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And now a brief break

• Oop! Its over.

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A Quick Little Addendum

• Metallic Bonding

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Metals

• Metallic bonds account for many physical
  characteristics of metals, such as
• Strength
• Malleability
• Ductility
• conduction of heat and electricity
• luster

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A Few Facts

• The outer electrons of metals are not very
  strongly held by the nucleus
• So they stray easily and can move from one atom
  to the next
• Think of a sea of electrons
• Outer energy levels overlap like covalent bonds

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Bond found in metals holds metal atoms
together very strongly
Metallic Bonds
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Metallic Bonds Mellow dogs with plenty of bones
to go around
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A Sea of Electrons
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Metals Form Alloys
Metals do not combine with metals. They form
Alloys which is a solution of a metal in a
metal. Examples are steel, brass, bronze and
pewter.
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The End