Covalent Bonds
No more stealing… time to share!
Review
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Ionic Bonds
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Positive and negative Ions are attracted to each other.
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Sort of like the north and south end of a magnet
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Positive Ions lose electrons
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Negative Ions gain electrons
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Happens between Metals and Nonmetals
COVALENT BOND
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The
bond formed by the
sharing
of electrons
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The force that holds the atoms together in a
covalent bond is the attraction of each atom’s
nucleus for the shared pair of electrons.
COVALENT BOND
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A force that bonds two atoms together by a sharing of
electrons
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Each pair of shared electrons creates
a bond
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Usually occurs between atoms of non-metals
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Example –
Water (H
2
O)
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O
H
H
Types of Covalent Bonds
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Different covalent bond types share a different
number of electrons
Single Bonds
Share 2
Electrons
Double Bonds
Share 4
Electrons
Triple Bonds
Share 6
Electrons
Water (H
2
O)
Carbon Dioxide (CO
2
)
Nitrogen (N
2
)
Polar and Nonpolar Covalent Bonds
Covalent bonds sometimes do not
share electrons equally…
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Polar = Unequally shared
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Examples: Water,
Ammonia, Carbon
Dioxide
… and sometimes they do.
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Nonpolar = Equally shared
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Examples: Diatomic Molecules
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Hydrogen (H
2
)
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Nitrogen (N
2
)
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Oxygen (O
2
)
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Fluorine (F
2
)
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Chlorine (Cl
2
)
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Iodine (I
2
)
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Bromine (Br
2
)
Polar Covalent Bonds
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Some atoms have a greater attraction for electrons
than other atoms
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Due to greater electronegativity
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When these atoms form a covalent bond, the
electrons will not be shared equally
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This is referred to as a polar covalent bond
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Unequal Sharing
(Polar Covalent Bond)
Why do you think the two Hydrogen atoms share
equally, but the Hydrogen and fluorine do not?
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Bonded hydrogen
atoms showing
equal sharing of
electrons
Hydrogen and
fluorine bond with
an unequal sharing
of electrons
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The unequal sharing of electrons between two atoms that
gives rise to negative and positive regions of electric
charge
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Results from an atom’s
electronegativity
– the ability to
attract electrons to itself
Electron
Cloud
Nonpolar Covalent Bond
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Some atoms have similar attraction for electrons, so the shared
pair(s) will be evenly distributed between each atom
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There are no “positive” or “negative” sides
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This is referred to as a nonpolar covalent bond
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Because there is no separation of charge within the molecule, they have little
or no attraction for one another
Nonpolar Covalent bonds
atoms share one
or more pairs of outer-shell electrons.
Oxygen
Atom
Oxygen
Atom
Oxygen
Atom
Oxygen
Atom
Oxygen
Molecule
(O
2
)
Oxygen
Molecule
(O
2
)