Using undergraduate physics and without resorting to numerical simulations the ratio of primordial H to He created in the Big Bang has been calculated and is in reasonable agreement with experimental results. The temperatures of critical events that led up to cosmological nucleosynthesis are fully derived. The conversion factor for the temperature-to-time scale is also derived and used to outline a timeline of the events that occurred at the beginning of the universe. At a time of 0.1 ms from the Big Bang and temperature of 1010 K, the weak interaction froze out of GUT and the proton-neutron ratio became constant. At 2 minutes and 10 seconds at a temperature of 109 K, the Deuterons formed. Finally, at approximately 300,000 years and 3700 K, neutral atoms (Hydrogen and Helium) were formed.