The number of electrons present in the antipenultimate shell of chlorine.

To determine the number of electrons present in the antipenultimate shell of chlorine, let us analyze the electronic configuration step by step. The antipenultimate shell refers to the shell that is two levels below the valence shell in an atom's electron structure.

Steps to Find the Number of Electrons

1. Chlorine has an atomic number of 17, which means it has 17 electrons distributed across different shells.
2. The valence shell (n) for chlorine is the third shell (n = 3). The penultimate shell, which is the shell before the valence shell, is the second shell (n - 1), and the antipenultimate shell, which is two levels below the valence shell, is the first shell (n - 2).
3. For chlorine:
   • Antipenultimate shell: n - 2 = 3 - 2 = 1
   • The first shell (the antipenultimate shell) contains 2 electrons, following the rule that the first shell can hold a maximum of 2 electrons.

Conclusion

The antipenultimate shell of chlorine is the first shell, and it contains 2 electrons. The penultimate shell, which is the second shell, contains 8 electrons, and the valence shell, or the third shell, contains 7 electrons. Thus, the electronic configuration of chlorine is 2, 8, 7.