CH1020 Exercises (Worksheet 4)
(Electronegativity, polarity of molecules, bond length, bond strength and bond order)
Using only the periodic table, predict the order of increasing electronegativity in
each of the following groups of elements:
Na, K, Rb
B, O, Ga
F, Cl, Br
S, O, F
Br, Cl, P
I, F, O
Rank the following bonds in order of increasing ionic character (Check
electronegativity values, Figure 9.19, page 352; Silberberg 4
N-O, Ca-O, C-F, Br-Br, K-F
Br-Br < N-O < C-F < Ca-O < K-F
Explain the difference between pure covalent bond and polar covalent bond.
Pure covalent: equal sharing of electron pair(s);
polar covalent: unequal
sharing of electron pair (s)
Explain the difference between polar covalent bond and ionic bond.
Polar covalent: unequal sharing of electron pair (s);
ionic bond: complete
transfer of electrons from one atom to another to form ions
Atoms X and Y have different electronegativities. Will the diatomic molecule X-
Y necessarily be polar?
What factors affect the size of the dipole
moment of a diatomic molecule?
If X and Y have different electronegativities, they have different
attractions for the electrons in the molecule.
The electron density around the
more electronegative atom will be greater, producing a charge separation or
dipole in the molecule.
Magnitude of the charges and the distance between them affect the size of the
dipole moment in a diatomic molecule.