Stretching Frequencies TABLE 12-1 Bond Stretching Frequencies. Bond Bond Energy [kJ(kcal)] Stretching Frequency(cm1) Frequency decreases with increasing atomic mass C一H 420(100)<note these are trs> 3000 C-D heavier 420(100) 2100 atoms v decreases C-C 350(83) 1200 Frequency increases with bond energy C-C 350(83) 1200 C=C 611(146) stronger 1660 bond 7 increases C=C 840(200) 2200 Frequency decreases with increasing atomic mass. Frequency increases with increasing bond energy. Chapter 12 8Chapter 12 8 Stretching Frequencies • Frequency decreases with increasing atomic mass. • Frequency increases with increasing bond energy. =>