TOPIC 4/14 – BOND AND MOLECULAR POLARITY
A. BOND POLARITY
(a)
POLAR BONDS
 result from a difference in _____________________ between bonding atoms
(i) IONIC BOND–very polar; involve _______of electrons from metal to nonmetal (ΔEN between 1.7 and 3.3)
e.g. calcium oxide (CaO); EN of Ca = _________ ; EN of O = ____________ ; ΔEN =
(ii) POLAR COVALENT BOND - “in-between” / somewhat polar bond (ΔEN is less than 1.7)
 a covalent bond in which electrons are shared ________________ ; resulting in a permanent ________________
 The end of the bond where the negatively charged electron cloud “spends more time” is labelled as being partially negative (δ-); the other end (i.e. the positive end) is
labelled “δ+”.
 electronegativity difference results in a bond ____________(represent bond dipoles using an arrow pointing from positive end to the negative end)
e.g. hydrogen chloride (HCl); EN of Cl = _________ ; EN of H = ____________ ; ΔEN =
(b) NON-POLAR
BONDS
(i) ‘Pure’ Covalent Bond - non-polar (ΔEN = 0)
 electrons are shared _____________ ; no permanent dipoles present
e.g. chlorine (Cl2)
B.MOLECULAR POLARITY
(a) NON-POLAR
MOLECULES
*a molecule:
 in which the charge is distributed _________________________ among the atoms making up the molecule
 that has either non-polar bonds (e.g. Cl2) or polar bonds whose bond dipoles cancel to __________
e.g. CO2
(b) POLAR
e.g. CH4
MOLECULES
*a molecule:
 in which the charge is distributed _________________________ among the atoms making up the molecule
 that has polar bonds with dipoles that do not cancel to zero
e.g. H2O
e.g. CH3Cl
**Note that both the ___________ of the molecule and the ______________ of the bonds within the molecule need to be considered in order to determine the overall polarity
of the molecule.
*DETERMINING MOLECULAR POLARITY(GENERAL SUMMARY)
MOLECULAR
SHAPE
1. a) LINEAR
b) LINEAR
2. a) TRIGONAL PLANAR
b) TRIGONAL PLANAR
“AXE”
BOND POLARITY
Notation
DIPOLES
CANCEL?
MOLECULAR EXAMPLES
POLARITY
(i.e. Resultant = ZERO?)
(i.e Polar or not?)
3. a) TETRAHEDRAL
b) TETRAHEDRAL
4. BENT
5. TRIGONAL
PYRAMIDAL
*For molecules types not in the table, sketch a shape diagram and consider the overall symmetry of the molecule.