# Homework Help: Calculating the energy level and radius for a helium atom

1. Jul 22, 2008

### ttk3

1. The problem statement, all variables and given/known data

Calculate the energy and radius for each of the five lowest (n = 1,2,3,4,5) electron orbits in a Helium atom with only one electron. Enter the energy as a positive value in units of "eV" and the radius in units of "nm". Hint: The Helium nucleus has 2 protons so Z = 2 and the ground state energy of Helium will be E0 = k(Ze)2/2r0.

2. Relevant equations

E = (E0/n2)*Z2
E0= 13.6 eV
Z2=4
r=(r0/Z)*n2
Z=2
3. The attempt at a solution

I got the correct answers for n = 1-2 and 4-5, but I cannot get the right answer for n=3. could you check my work?

The answers I got were E = 6.044 eV and r = .238 nm

2. Jul 23, 2008

### G01

I am getting the same numbers you are ttk3. The process for finding the answer for n=3 is the same as it is for the other four you got correct, so I don't see how you could get only n=3 incorrect.

Are you sure there isn't some error or typo in wherever you are getting the correct answer from?