Electronic configuration of 1st period:
In 1 period only two elements are present. This period starts with the filling of electrons in first energy level, n-1 . This level has only one orbital as is. Therefore it can accommodate two electrons maximum.
Electronic configuration of 2nd period:
In the 2’ period 8 elements are present. This period starts with filling of electrons in the second energy level, n = 2. In this level four orbitais (one 2s and three 2p) are present. Hence the second energy level can accommodate 8 electrons. Thus, second period has eight elements.
