COVALENT BONDING
IONIC OR COVALENT?
•CARBON DIOXIDE
•CALCIUM CARBIDE
•RUBIDIUM BROMIDE
•SILICON TETRACHLORIDE
•HYDROGEN SULFIDE
•WATER
NOMENCLATURE
CO2
Sr3N2
P2O5
PCl3
Na2O
H2O
KOH
LiBr
N2O5
SO2
FORMULA WRITING
SILICON DIOXIDE
NICKEL (III) SULFIDE
DIBORON TETRABROMIDE
CARBON TETRACHLORIDE
ALUMINUM HYDROXIDE
DINITROGEN TRIOXIDE
AMMONIUM CHLORIDE
LEAD (IV) OXIDE
WORKSHEETS
15 MINUTES
NON-POLAR COVALENT
• Two or more non-metals
• Equal or almost equal sharing of electrons
• Electronegativity difference of < 0.4
EXAMPLES:
N-N (3.0 – 3.0 = 0.0)
Cl-Br (3.0 – 2.8 = 0.2)
POLAR COVALENT
• Two or more non-metals
• Unequal sharing of electrons
• Electronegativity difference of 0.5 to1.7
EXAMPLES:
Cl – C (3.0 – 2.5 = 0.5)
O – S (3.5 – 2.5 = 1.0)
IONIC
Ionic compounds are the MOST polar. The elements involved in
an ionic bond always have a large difference between their
respective electronegativity values. This large difference results
in the “transfer” of an electron. The element “giving” the
electron takes on a positive charge while the element “taking”
the electron takes on a negative charge.
SHOWING POLARITY
• One end has a partial positive charge (the less
electronegative atom) and the other has a
partial negative charge (the atom that is
holding on to the electrons)
• Represented by: δ+ and δ- (in the Lewis
diagram) – these are called dipoles – they
cause attraction between molecules
DETERMINING POLARITY
To determine the polarity of a compound, a series of steps must be
taken:
1) Represent the compound using Lewis dot structures.
2) Understand that EACH bond will have a different polarity. The final
polarity of a compound is determined as the sum of each individual
polarity created by the bonds. The shape of the molecule is also a
factor.
• Look up the electronegativity of each element. If the difference
between the electronegativity for the bonded elements is less than
0.4, it is non-polar. If the difference is 0.5 to 1.7, it is polar. The
MORE electronegative end of the bond has a negative charge, while
the LESS electronegative end of the bond has a positive charge.
LEWIS DIAGRAM STEPS
1. Count number of valence electrons in all atoms.
2. Draw the central atom(s) with its/their valence electrons –always the least
electronegative (exception - Never H).
3. Draw single bonds between outer atoms and central atom(s). Determine
available electrons (total valence – (2×# single bonds).
4. Arrange remaining electrons in pairs around the outside atoms first, the central
atom second.
5. If necessary to complete the octet on the central atom, move lone pairs from
outer atoms to form multiple bonds.
LEWIS STRUCTURE REVIEW
H2O
CF4
CO2
CCl4
POLARITY EXAMPLES
HCl
CO2
CCl4
H2O