1. Compute the ground state energy and first excited state energy of a one electron species with Z = 5. E = -(Z^2*e^2)/(8*pi*epsilon 0*a*n^2). 2. I cannot for the life of me figure out how to find "a." 3. I know from the question that Z=5 and I assume e=-1.6e-19 C because the pi epsilon 0 thing would go with permittivity constant which allows unit cancellation and n=1 for ground state and n=2 for first excited state. The only problem is I cannot figure out what "a" is so I cannot attempt to answer the question. Help?