question_answer

What is the maximum number of electrons that can be present in an atom in which the highest principal quantum number is 4?

Answer:

                Keeping in view aufbau principle, the electronic configuration of atom having highest value of n = 4 will be \[1\,{{s}^{2}}\,2\,{{s}^{2}}\,2{{p}^{6}}\,3\,{{s}^{2}}\,3{{p}^{6}}\,4\,{{s}^{2}}\]\[3\,{{d}^{10}}\,4\,{{p}^{6}}\] (After 4p, filling of 5s starts) Hence, maximum number of electrons present = 36 (Kr).