Covalent Bonds: The Joy of Sharing!
Covalent Bonds: The Joy of Sharing!
Covalent Bonds: The Joy of Sharing!
CCl4 O2
N2 CO
Lewis structures (electron dot structures)
show the structure of molecules. (Bonds
can be shown with dots for electrons, or
with dashes: 1 dash = 2 electrons)
H2 HBr
CCl4 O2
N2 CO
Lewis structures (electron dot structures)
show the structure of molecules. (Bonds
can be shown with dots for electrons, or
with dashes: 1 dash = 2 electrons)
H2 HBr
CCl4 O2
N2 CO
Lewis structures (electron dot structures)
show the structure of molecules. (Bonds
can be shown with dots for electrons, or
with dashes: 1 dash = 2 electrons)
H2 HBr
CCl4 O2
N2 CO
Lewis structures (electron dot structures)
show the structure of molecules. (Bonds
can be shown with dots for electrons, or
with dashes: 1 dash = 2 electrons)
H2 HBr
CCl4 O2
N2 CO
Lewis structures (electron dot structures)
show the structure of molecules. (Bonds
can be shown with dots for electrons, or
with dashes: 1 dash = 2 electrons)
H2 HBr
CCl4 O2
N2 CO
Octet Rule
OH- N22-
NO3- CO32-
SO42- NH4+
Lewis Structure Examples:
CO2- CBr3-
OH- N22-
NO3- CO32-
SO42- NH4+
Lewis Structure Examples:
CO2- CBr3-
OH- N22-
NO3- CO32-
SO42- NH4+
Lewis Structure Examples:
CO2- CBr3-
OH- N22-
NO3- CO32-
SO42- NH4+
Lewis Structure Examples:
CO2- CBr3-
OH- N22-
NO3- CO32-
SO42- NH4+
Lewis Structure Examples:
CO2- CBr3-
OH- N22-
NO3- CO32-
SO42- NH4+
Lewis Structure Examples:
CO2- CBr3-
OH- N22-
NO3- CO32-
SO42- NH4+
Lewis Structure Examples:
CO2- CBr3-
OH- N22-
NO3- CO32-
SO42- NH4+
Electronegativity
The ELECTRONEGATIVITY of an
element is: the tendency for an
atom to attract electrons to itself
when it is chemically combined with
another element.
The result: a tug-of-war
between the nuclei of the
atoms.
Electronegativity
Electronegativities are given numerical
values (the most electronegative element
has the highest value; the least
electronegative element has the lowest
value)
**See Figure 6-18 p. 169 (Honors)
Most electronegative element:
Fluorine (3.98)
Least electronegative elements:
Fr (0.70), Cs (0.79)
Electronegativity
Notice the periodic trend:
As we move from left to right across a row,
electronegativity increases (metals have low
values nonmetals have high values excluding
noble gases)
As we move down a column, electronegativity
decreases.
The higher the electronegativity
value, the greater the ability to
attract electrons to itself.
Nonpolar Bonds
Example: HCl
Electronegativities:
H = 2.20
Cl = 3.16
+ H -
Cl
Polar Bonds
Example: H2O
Electronegativities:
H = 2.20
O = 3.44
Polar Bonds
Example: H2O
Electronegativities:
H = 2.20
O = 3.44
Polar Bonds
Example: H2O
Electronegativities:
H = 2.20
O = 3.44
Predicting Bond Types
Electronegativities help us predict the
type of bond:
Electronegativity Type of Bond Example
Difference
covalent
0.00 0.40 H-H
(nonpolar)
covalent
0.41 1.00 H-Cl
(slightly polar)
1.01 2.00 covalent H-F
(very polar)
2.01 or higher ionic Na+Cl-
Polar Molecules
Example: CO2