Organic Structures - Organic Chemistry Concepts: An EFL Approach - page 10

QUESTIONS AND PROGRAMS
Q 1.1. Draw the unshared electron pairs ( lone pairs ) that are missing from the
following molecules.

Q 1.2. Identify the most electronegative element(s) in each of the molecules in
Q 1.1 above.

PROGRAM 1 Percentage Ionic Character of Covalent
Bonds
A Covalent bond polarity can be given as a percentage of ionic character. This is
calculated from the electronegativities E a and E b of the more and less electronegative
atoms in the bond.

Use the values in Appendix 1 to calculate the ionic character of the covalent single
bonds in C-O, C-H, and O-H. Show the partial charges for each bond.

B Simple calculation gives:

Q 1.3. In each of the following sets, arrange the covalent bonds in an order of
increasing partial ionic character (i.e., increasing polarity ).

(a) C-H, O-H, N-H (b) C-H, B-H, O-H (c) C-S, C-O, C-N

(d) C-Cl, C-H, C-I (e) C-N, C-F, B-H (f) C-Li, C-B, C-Mg