Stretching Frequencies Bond Energy Stretching Frequency Bond [kcal (kJ)] (cm-) Frequency dependence on atomic masses C一H 100(420) 3000 C一D heavier 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) bond 1660 7 increases C=C 200 (840) 2200↓ Frequency decreases with increasing atomic weight. Frequency increases with increasing bond energy. Chapter 12 Chapter 12 8 Stretching Frequencies • Frequency decreases with increasing atomic weight. • Frequency increases with increasing bond energy. =>