The principal quantum number for the second period is 2.
Principal quantum number
Principal quantum numbers are denoted by the symbol ‘n’. They designate the principal electron shell of the atom. Since the most probable distance between the nucleus and the electrons is described by it, a larger value of the principal quantum number implies a greater distance between the electron and the nucleus.
- The second period has a principal quantum number of 2 in the modern periodic table.
- In addition, there are 2s and 2p orbitals in the second period, which will be filled.