PART II
Covalent
Bonds
LET’S
FIRST
REVIEW
IONIC
BONDING
In an IONIC bond,
electrons are lost or gained,
resulting in the formation of IONS
in ionic compounds.
F
K
F
K
F
K
F
K
F
K
F
K
F
K
F
K
+1
-1
F
K
+1
-1
The compound potassium fluoride
consists of potassium (K+) ions
and fluoride (F-) ions
F
K
+1
-1
The ionic bond is the attraction
between the positive K+ ion
and the negative F- ion
IONIC BOND
Formula KF
So
what
are
covalent
bonds?
In covalent bonding,
atoms still want to achieve
a noble gas configuration
Of eight electrons in the
outermost shell (the octet rule).
In covalent bonding,
atoms still want to achieve
a noble gas configuration
(the octet rule).
But rather than losing or gaining
electrons,
atoms now share an electron pair.
In covalent bonding,
atoms still want to achieve
a noble gas configuration
(the octet rule).
But rather than losing or gaining
electrons,
atoms now share an electron pair.
The shared electron pair
is called a bonding pair
Covalent bonding is the SHARING of electrons
when electrons are shared equally
NONPOLAR �COVALENT BONDS
Non-Metal with Non-Metal
Ex H2 or Cl2
Cl2
Chlorine forms covalent bond with itself
Cl
Cl
How
will
two
chlorine
atoms
react?
Cl
Cl
Each chlorine atom wants to
gain one electron to achieve an octet
Cl
Cl
Neither atom will give up an electron –
(chlorine is highly electronegative).
What’s the solution – what can they
do to achieve an octet?
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
octet
Cl
Cl
circle the electrons for
each atom that completes
their octets
octet
Cl
Cl
circle the electrons for
each atom that completes
their octets
The octet is achieved by
each atom sharing the
electron pair in the middle
Cl
Cl
circle the electrons for
each atom that completes
their octets
The octet is achieved by
each atom sharing the
electron pair in the middle
Cl
Cl
circle the electrons for
each atom that completes
their octets
This is the bonding pair
Cl
Cl
circle the electrons for
each atom that completes
their octets
It is a single bonding pair
Cl
Cl
circle the electrons for
each atom that completes
their octets
It is called a SINGLE BOND
Cl
Cl
circle the electrons for
each atom that completes
their octets
Single bonds are abbreviated
with a dash
Cl
Cl
circle the electrons for
each atom that completes
their octets
This is the chlorine molecule,
Cl2
O2
Oxygen is also one of the diatomic molecules
(Di-two Atomic-atoms)
How will two oxygen atoms bond?
O
O
O
O
Each atom has two unpaired electrons
O
O
O
O
O
O
O
O
O
O
O
O
Oxygen atoms are highly electronegative.
So both atoms want to gain two electrons.
O
O
Oxygen atoms are highly electronegative.
So both atoms want to gain two electrons.
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
Both electron pairs are shared.
6 valence electrons
plus 2 shared electrons
= full octet
O
O
6 valence electrons
plus 2 shared electrons
= full octet
O
O
two bonding pairs,
O
O
making a double bond
O
O
=
For convenience, the double bond
can be shown as two dashes.
O
O
O
O
=
This is the oxygen molecule,
O2
this is so cool!!
when electrons are shared but shared unequally
POLAR COVALENT BONDS
Still Non-Metal to Non-Metal
Ex. H2O
- water is a polar molecule because oxygen is more electronegative than hydrogen, and therefore electrons are pulled closer to oxygen.