(a) The energy of an electron in the 4s state of sodium is -1.947eV. What is the effective net charge of the nucleus "seen" by this electron? On the average, how many electrons screen the nucleus?
(b) For an outer electron in the 4p state of potassium, on the average 17.2 inner electrons screen the nucleus. (i) What is the effective net charge of the nucleus "seen" by this outer electron? (li) What is the energy of this outer electron?