Final answer:
In a nitrogen atom, an electron experiences the greatest shielding in the 3s orbital. The spherical shape of s orbitals allows them to shield other electrons in the same shell, leading to more shielding of the electrons as the principal quantum number increases.
Step-by-step explanation:
An electron in a nitrogen atom experiences the greatest shielding in the 3s orbital.
Shielding occurs when inner electrons block the attraction of the nucleus for the outer electrons, making them less stable and thus higher in energy.
From the given options, A. 3p, B. 2p, C. 1s, D. 3s, and E. 2s, the correct answer is D. 3s.
The spherical shape of the s orbitals allows them to shield electrons in the same shell but different (p, d, f) subshells effectively.
As the principal quantum number (n) increases, the size of the orbital increases, and the electrons experience more shielding due to them being farther from the nucleus.
Hence, an electron in the 3s orbital would experience more shielding than electrons in the 1s, 2s, or 2p orbitals, due to being in a higher principal energy level with more inner electrons in place to provide shielding.