# Full ionization meaning

I'm confused as to what full ionization mean? I have the mean molecular weight of electrons and ions and I have to calculate the ideal gas pressure for a star. Do I have to add them up as usual or do I use only the mean molecular weight of ions?

• The proton mass is about 2000 times the electron mass, so it might be reasonable to neglect the electrons entirely. Depends on the accuracy of your calculation. – Kyle Kanos Apr 13 '15 at 17:50