Stretching Frequencies Bond Energy Stretching Frequency Bond [kcal (kJ)] (cm-1) Frequency dependence on atomic masses 100(420) 3000 heavier C-1 100 (420) 2100 v decreases C-C atoms 83 (350) 1200 Frequency dependence on bond energies C-C 83 (350) 1200 stronger C=C 146 (611) 7 increases bond 1660 C≡C 200 (840) 2200 Frequency decreases with increasing atomic weight. Frequency increases with increasing bond energy. Chapter 12 8Chapter 12 8 Stretching Frequencies • Frequency decreases with increasing atomic weight. • Frequency increases with increasing bond energy. =>