Computational chemistry can quantify the inductive effect of different substituents in a molecule. An example of the inductive effect is the impact of charge-dipole interactions within the 2,2,2-trifluoroethylammonium ion. The inductive effect for 2,2,2-trifluoroethylamine is taken to be the difference in proton affinity (PA) between 2,2,2- trifluoroethylamine and ethylamine. The proton affinity is the enthalpy change when a molecule reacts in the gasphase with a proton. The proton affinity can be determined using quantum calculations of the energy difference between the most stable conformations of the amine and its conjugate acid. These calculations were performed using Molden graphics and Gaussian 09 quantum software to determine the energy differences. The PA values were calculated from a high-level method, which gives a close fit to experimental results. Our calculations, consistent with experimental values, show a significant decrease in proton affinity from ethylamine to 2,2,2- trifluoroethylamine. As expected, 2,2-difloroethylamine has a greater PA than 2,2,2-trifluoroethylamine confirming that two fluorine atoms exert less influence on the ammonium ion than three fluorine atoms. Comparing the PA between amines with fluorine versus chlorine substituents allows quantification of the difference in the inductive effects of the two halogens a consequence of the difference in their electronegativity. We also examine how factors such as distance between charge and dipole, intramolecular hydrogen bonding, and solvation influence the inductive effect. Such a fundamental quantitative understanding of the inductive effect will permit chemists to make better predictions to control chemical reactions.