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Covalent Bonds
Understanding how oil and water
can be made to mix together.
What are covalent bonds?
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Covalent bonds occur when
two or more atoms come
together and share an
electrons.
The force that holds atoms
together in a covalent bond
is the attraction of each
atom’s nucleus for the
shared pair of electrons.
Examples of molecules with
covalent bonds are NH3, F2,
O2, N2, and CO2.
Multiple bonds
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Double and triple bonds are
common in covalent atoms.
A bond between two atoms
contains two electrons, and is
represented by two dots
between two elements.
A double bond contains four
electrons and produces two
bonds.
A triple bond contains six
electrons and produces three
bonds.
Oxygen (O2) has a double bond,
while (N2) has a triple bond.
Molecular compounds
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Molecules come together
to produce a molecular
compound.
Compared to ionic
compounds molecular
compounds have lower
melting points and boiling
points.
Molecular compounds also
do not conduct electricity
when dissolved in water or
melted. (NaCl and water is
an ionic combination by
comparison).
Comparing molecular and ionic bonds
Substance
Formula
Melting point boiling
(Degree C)
(Degree C)
Methane
CH4
-184.4
-161.5
Rubbing
alcohol
C3H8O
-89.5
82.4
Zinc chloride ZnCl2
290
732
Magnesium
chloride
714
1412
MgCl2
An unequal sharing of electrons
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In molecular compounds the
electrons are not distributed
equally through the
molecule.
The result is a molecule
which has a slight charge to
it as a entire molecule.
The need to possess all of
the atoms is similar to a
game of tug of war, except
the molecule is having this
battle with itself.
Polar and nonpolar bonds.
► Polar
covalent bonds occur
when electrons are shared
unevenly which produces a
positive and a negative end of
a molecules. (HF acid, and H2O
are examples.)
► Water is the universal solvent
► Non polar covalent molecules
occur when electrons are
shared equally by the atoms in
a molecule. (F2, and CO2 are
examples)
Understanding how oil and water
can mix.
► Water
contains polar bonds and
oil contains non polar bonds.
► Detergent is a large molecule
which has a polar bond at one
end and a non polar bond at
the other.
► The detergent acts like a glue
which binds both water and oil
to itself on opposite ends in
order to remove oil from a
substance while being
suspended in a water solution.