# Ionization of hydrogen in the sun

1. Feb 18, 2012

### lycraa

1. The problem statement, all variables and given/known data
in part 1 i used the Saha equation to calculate that the hydrogen in the center of the sun was fully ionized (given temperature and central electron density). part 2 says:

Re-examine the result by computing the average separation of atoms at the center of the sun knowing the radius of the first Bohr orbital.

I'm a little lost here. this would be no problem if i was given the atom density, but I'm not sure how to deal with the electron density

2. Feb 18, 2012

### cepheid

Staff Emeritus
How many electrons are there per atom, for hydrogen? What does that tell you about the number density of hydrogen atoms, given the number density of electrons?

3. Feb 18, 2012

### lycraa

well, for NON ionized hydrogen, you would have only one electron. meaning that the number density would be the same as the electron density. So would i be right in saying then, that if the average separation i found using the electron density equals 2* bohr radius, i would have mostly non ionized hydrogen?

4. Feb 18, 2012

### cepheid

Staff Emeritus
I'm not sure why you have "NON" in all caps. I mean, if you take hydrogen and ionize it, you're still going have equal numbers of protons and electrons. Extra electrons don't just appear out of nowhere.

I'm sorry, but I don't know the answer to that. On the one hand, this does seem to be the tree up which this problem is barking, by having you reconsider your previous result, and showing that these supposedly "free" electrons don't have much room to move around. On the other hand, I had always thought that the solar core consisted of charged particles, especially since people always talk of the fusion reaction consisting of free protons combining together to form helium nuclei. Besides, although those electrons may, on average, have a mean free path that is not much larger than the orbital of a bound electron, they are still too energetic to remain bound, which would have me lean more towards the ionized picture. EDIT: Remember that I said that I just don't know for sure.